Windows Services in C#: Controlling Your Service from Another Application (part 6)

If you’ve ever used SQL Server, you know it comes with a little control program that allows you to start and stop the SQL Server service. Wouldn’t it be cool if you could write a small program to do the same with your service? Well you can, and today we’ll learn how.

Before we begin, I made a few little tweaks to the TimeLoggerService source code that will make it a bit easier to work with, and implement some of the things we’ll want to do in our control program.

    public TimeLoggerService()
    {
      InitializeComponent();
      // Set the timer to fire every twenty seconds
      // (remember the timer is in millisecond resolution, 
      //  so 1000 = 1 second. ) 
      _timer = new Timer(20000);
 
      // Now tell the timer when the timer fires 
      // (the Elapsed event) call the _timer_Elapsed 
      // method in our code
      _timer.Elapsed += new 
        System.Timers.ElapsedEventHandler(_timer_Elapsed);
    }
 
    private void WriteToLog(string msg)
    {
      EventLog evt = new EventLog(“ArcaneTimeLogger”);
      string message = msg + “: “
        + DateTime.Now.ToShortDateString() + ” “
        + DateTime.Now.ToLongTimeString();
      evt.Source = “ArcaneTimeLoggerService”;
      evt.WriteEntry(message, EventLogEntryType.Information);
    }
 
    protected override void OnStart(string[] args)
    {
      _timer.Start();
      WriteToLog(“Arcane Start”);
    }
 
    protected override void OnStop()
    {
      _timer.Stop();
      WriteToLog(“Arcane Stop “);
    }
 
    // This method is called when the timer fires
    // it’s elapsed event. It will write the time
    // to the event log. 
    protected void _timer_Elapsed(object sender, ElapsedEventArgs e)
    {
      WriteToLog(“Arcane Timer”);
    }

In the class constructor, the only change I made was to change the time from 60 seconds (60000 milliseconds) down to 20 seconds (20000 milliseconds). To be honest I got tired of waiting on it to log for my tests.

Next, I created a “WriteToLog” method that handles the actual writing of a message to the event log. This code is identical to what was previously in the timer_Elapsed event, except I take a passed in message and append the current date/time to the log. Note one other change, I modified it to use the LongTimeString instead of ShortTimeString, so I could get the seconds to display.

I then modified the OnStart and OnStop to log start and stop messages for me, which is probably a good idea for your service to do too. Finally I modified the _timer_Elasped event where I’d taken the WriteToLog code from, and made a call to our new method. OK, that takes care of changes to the windows service.

Now, let’s add a new project to our solution. In the Solution Explorer, right click on the solution name and pick Add Project, then pick Windows Application. Note that we could do this with a command line app or class library as well, but for this demo we’ll use a windows form. I gave my new app the imaginative name of “TimeLoggerManager”.

I renamed the Form1 to TLManager, and allowed VS to rename all the occurances of Form1 for me. I’m now going to add a few basic controls, one label (lblStatus), and two command buttons (btnStart and btnStop). I’m also going to add a timer control, tmrRefresh. Set the timer to enabled and pick a reasonable time, maybe every 10 or 15 seconds (10000 or 15000 in the Interval property, remember it gets set in milliseconds as well).

In order to use some of the classes we’ll need, we must set a reference to the System.ServiceProcess assembly. Right click on the TimeLoggerManager and Add Reference, then on the .Net tab scroll down to System.ServiceProcess, click on it and press OK.

Now switch to code view on the form, and in the using area add a “using System.ServiceProcess” reference.

The first thing we need to do is find out what the status is of the service event. To do this we’ll first get a reference to our service by creating a ServiceController object, note in the “new” area we have to pass in the name of our service in order to get a reference to it. Once our object is created, I’ll pass it to a method that will set everything up for the form.

      ServiceController sc = new ServiceController(“ArcaneTimeLogging”);
      SetDisplay(sc);

Set Display is a custom method I wrote, here’s it’s code:

    private void SetDisplay(ServiceController sc)
    {
      sc.Refresh();
      if (sc.Status == ServiceControllerStatus.Stopped)
      {
        btnStop.Enabled = false;
        btnStart.Enabled = true;
        lblStatus.Text = “Stopped”;
      }
      if (sc.Status == ServiceControllerStatus.Running)
      {
        btnStart.Enabled = false;
        btnStop.Enabled = true;
        lblStatus.Text = “Running”;
      }
    }

The first thing called is sc.Refresh, this will cause the ServiceController to update all of the properties in our sc object with the correct values. Next I can query the Status property of our SC object, and set my command buttons and labels appropriately.

Starting and stopping our service is just as easy, all we have to do is create an instance of a service controller object, and then call it’s Start or Stop method.

    private void btnStart_Click(object sender, EventArgs e)
    {
      ServiceController sc = new ServiceController(“ArcaneTimeLogging”);
      sc.Start();
      btnStart.Enabled = false;
      btnStop.Enabled = true;
      lblStatus.Text = “Running”;
      sc.Refresh();
    }
 
    private void btnStop_Click(object sender, EventArgs e)
    {
      ServiceController sc = new ServiceController(“ArcaneTimeLogging”);
      sc.Stop();
      btnStop.Enabled = false;
      btnStart.Enabled = true;
      lblStatus.Text = “Stopped”;
      sc.Refresh();
    }

Because you can also start and stop the service from other locations, like VS or the MMC, it’s important to keep the display in sync. In the event for the timer, all we have to do is create another reference and pass it to the same SetDisplay method so everything stays in sync.

    private void tmrRefresh_Tick(object sender, EventArgs e)
    {
      ServiceController sc = new ServiceController(“ArcaneTimeLogging”);
      SetDisplay(sc);
    }

Go ahead and give it all a try. Start your service, then check it in the MMC. Use MMC to stop the service, then watch the app automatically update to reflect the status.

Tomorrow we’ll look at sending commands to our windows service, then to wrap up the series we’ll look at integrating the event log into our application. Stay tuned!

Arcane Holiday

Today in the US we are celebrating Memorial Day, where we remember all of the soldiers who fell in battle. So let me first start by thanking the families and those men who sacrificed themselves for the greater good.

In keeping with the holiday theme, I thought I’d take a brief holiday from the Windows Services series and catch up on a few things.

First, there’s been an update to my favorite Windows add-on, TouchCursor. The new version fixes the issue I mentioned with Virtual PC’s. The only issue since I’ve run across is in using it with Visual Studio and DevExpress CodeRush add-in. CodeRush also wants to use the spacebar for activation. However, I was able to easily change the activation key from CodeRush to something else, and problem was solved. Check it out at http://touchcursor.com/ or see my initial review at http://shrinkster.com/pf4 .

Next, about a week ago I mentioned some great music to program to by a group called Midnight Syndicate. Shortly after posting I found out the Haunted Voices Radio podcast did an entire weekend of Midnight Syndicate, including playing their music and complete interviews. Check out Haunted Voices Radio at http://www.hauntedvoicesradio.com/modules.php?name=Content&pa=showpage&pid=6 or http://shrinkster.com/pf2 . Each banner ad is to a separate MP3 (the weekend was broken up into 2 hour chunks for easy downloads). I believe there are 17 in all.

Finally I have to confess to a guilty pleasure. I recently received a gift certificate to a book store, and used it to purchase “Windows Developer Power Tools” by James Avery and Jim Holmes. (Amazon link: http://shrinkster.com/pf5 )

If you’ve been reading my blog for a while you know I’m a “tool freak”, I love add-ins and tools for Windows and Visual Studio. As such I’ve been wanting this book for a while, but since I’ve already got a huge stack of books I’m still reading through I was having problems justifying yet another book. The gift certificate gave me just the opportunity I needed to get this cool new book. At over 1200 pages it’s chock full of toys, can’t wait to dig in!

Arcane Thoughts: Thinking Inside the Box

Today I’m at an offsite meeting, talking about a new project. I won’t get into too many specific details, but we have to pull data from a web service and update an Oracle database. We can use a vendor provided Java API that runs on a Unix box to do the updates, or we can write to the database directly as long as we handle integrity issues.

So we spent the day brainstorming, to come up with possible solutions. Here is the list of contenders:

Write a Java app that runs on Unix that uses the vendor API’s.
Write a Java app that runs on Unix and updates the database directly.
Write a C# app that runs on a Windows Server, where a Batch Scheduler will kick it off.
Write a C# app that runs as a Windows Service under XP (we haven’t taken the Vista plunge at work yet).
Write a SQL Server Integration Services package that is run by the SQL Server job scheduler. It will use the web service as the input and update Oracle.
Use one of the above methods to pull the data then let BizTalk process it from there.

We haven’t made a decision yet, and my point was not so much to talk about the pro’s and cons of each solution. Instead it’s to get you to think creatively when it comes to new solutions for your company. Sitting down and cranking out yet another C# or VB.Net app may not always be the best approach. You may have a task you can accomplish with less code by using SQL Server Integration Services. Or maybe BizTalk might fit the bill.

All too often as programmers our first answer to any solution is to pull up Visual Studio and start grinding out code. Take some time though, to explore a few other options. There’s a rich set of tools out there, and sometimes the best solution to a programming problem may not be programming.

SQL Server Compact Edition To Be Shipped With Windows Mobile 6.0!

I was relaxing Monday evening, watching some of Channel 9 videos I’d downloaded (yeah, I know, but I really do find it relaxing). In this video on Windows Mobile 6: http://channel9.msdn.com/Showpost.aspx?postid=303900 Rory is interviewing Mel Sampat who showed off some cool stuff with Windows Mobile 6.0.

One of the coolest things is that WM6 includes both SQL Server Compact Edition and .Net Compact Framework 2.0. What this means for you as a developer is that you don’t have to worry about deploying all the SSCE plumbing. How sweet will that be!

They also demoed some cool voice capabilities that you have to see. Very very awesome.

Now if they’d just hurry up and release Windows Mobile 6!!

SQL Server 2005 Compact Edition – Important Component

In my post on Getting Started with SQL Server ( http://shrinkster.com/nsk ), I mentioned 3 things you need. SQL Server CE, Visual Studio 2005 SP 1, and the SQL Server CE Books on Line. As it turns out there’s an important fourth item.

The missing component is the “Microsoft SQL Server Compact Edition Tools for Visual Studio 2005 Service Pack 1”, available at http://www.microsoft.com/downloads/details.aspx?familyid=877C0ADC-0347-4A47-B842-58FB71D159AC&displaylang=en or http://shrinkster.com/oam .

This service pack fixes a few things using SSCE with VS, one of them I consider critical. When you do a Project, References from VS, in the .Net list you will now be able to find a selection for System.Data.SqlServerCe.

Second, all of the Create Database dialogs now correctly read “SQL Server Compact Edition” instead of “SQL Server Mobile”. It also updates device CAB files correctly and includes new features such as Click Once support.

This should be installed fourth in your list, so if you’ve already done the other components, you are good to go for installing this. To recap:

Install SQL Server Compact Edition components. (http://shrinkster.com/l9f).
Install Visual Studio Service Pack 1. (http://shrinkster.com/lel )
Install SQL Server CE Books On-line. ( http://shrinkster.com/lem )
Install SSCE for VS SP1, as I’ve described here. ( http://shrinkster.com/oam).

A special thanks to Doug Tunure, our regional MS Developer Evangelist who helped me communicate with the SSCE team to figure out what was missing, and thanks to the SSCE team for a great tool.

System Views in SQL Server Compact Edition: Provider Types

The last view we’ll discuss is the INFORMATION_SCHEMA.PROVIDER_TYPES. Strictly speaking, this does not provide a view into your particular database, but into SQL Server Compact Edition. As such, it probably won’t be very useful in day to day queries into the database.

What it may be useful for is in automating database code generation. This table lists all of the valid database types that SQL Server CE supports. Presumably if Microsoft chooses to add new data types to SSCE they will show up here.

Let’s take a look at the query that’ll return some useful info, and what each field means.

select type_name, data_type, column_size, 
       literal_prefix, literal_suffix,
       is_nullable, case_sensitive, 
       unsigned_attribute, fixed_prec_scale,
       minimum_scale, maximum_scale, is_fixedlength 
 from information_schema.provider_types
 

type_name contains the list of valid datatypes, such as int, real, nvarchar, etc.

data_type contains a numeric representation of the type of data stored in the field. Note this is not unique, for example nchar and nvarchar, and ntext all have the same data_type of 130.

Column_size indicates the max size for a data_type.

Literal_prefix / literal_suffix indicates what you should use to wrap a literal value. This is probably one of the more useful items in this table. Let’s say you have a static text value you want to insert into a SQL statement, perhaps a system name such as the word arcanecode.com. Looking up the literal_prefix for a ntext item I see that it is N’ (the letter N followed by a single quote). The literal_suffix is just a single quote mark, so to include in a SQL statement I’d need to put N’arcanecode.com’ .

Is_nullable is obvious, a 1 indicates the field is allowed to hold null values, a 0 means it can’t. As of this writing, all the field types in SSCE are nullable.

Case_sensitive is similar, 1 shows the field is case sensitive, 0 not. Again, as of this writing none of the fields in SSCE are case sensitive.

Unsigned_attribute is null for non-numeric type, but for numbers a 1indicates the data_type is unsigned only (i.e. no negative values allowed). A 0 indicates negative values are valid.

Fixed_prec_scale is another Boolean field. A 1 indicates the precision (the number of positions after the decimal point) is fixed. A 0 indicates you can change the precision.

Minimum_scale, maximum_scale is tied to the fixed_prec_scale. For items like int’s where the precision is always the same, this is null. However on numerics the user (i.e. you) can set the scale, and these fields indicate the valid range.

Is_fixedlength is a Boolean that flags whether the data_types length is fixed. For numerics this is going to be 1 (true), and for most text types this is 0 (false).

If nothing else this table makes a great quick reference. Since SSCE only supports a subset of the SQL Server data types, it’s handy to have a place to see which types are supported.

In your application, you could use this to build code generators or build SQL statements to create new databases. For example you could use it to look up the prefix / suffix types for a data_type.

And there you go, this completes a week long look at the various views built into SQL Server 2005 Compact Edition, and how you can use them within your applications.

System Views in SQL Server Compact Edition: Constraints

Constraints are actually found in two views, INFORMATION_SCHEMA.TABLE_CONSTRAINTS and INFORMATION_SCHEMA.KEY_COLUMN_USAGE. Let’s look at table constraints first.

select constraint_name, table_name, constraint_type 
  from information_schema.table_constraints;

This returns a simple list of the names of the constraints for each table with a constraint in your system. If the table does not have a constraint, it won’t be found here. Finally, the constraint type will either read “PRIMARY KEY” or “FOREIGN KEY”.

To gather more info about constraints, we have to shift to the key_column_usage view. This view shows the fields associated with a constraint.

select constraint_name, table_name, column_name, ordinal_position
  from information_schema.key_column_usage;

By now most of these fields should be familiar. You’ll note though the one drawback, within this view there’s no way to tell whether the constraint is a primary key or foreign key. However, a little SQL magic to combine these two views will solve this dilemma.

select kcu.constraint_name, tc.constraint_type, kcu.table_name, 
       kcu.column_name, kcu.ordinal_position
  from information_schema.key_column_usage kcu,
       information_schema.table_constraints tc
 where kcu.constraint_name = tc.constraint_name;

You should know there is another table that lists constraints, the INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS. This view only shows referential constraints, not primary keys. In this case we’re interested in documenting all constraints, so there’s nothing here we cannot gather from the other two tables.

And there you go, a simple way to determine the constraints attached to the tables in your SQL Server 2005 Compact Edition tables.

System Views in SQL Server Compact Edition: Indexes

Knowing what indexes are available can help you speed access to your database. While the indexes view has a lot of fields, there’s only a handful that are really useful to us.

select table_name, index_name, primary_key, 
       [unique], ordinal_position, column_name 
  from information_schema.indexes;
 
Table_name and column_name are obvious, as is the index_name field. The primary_key will be 1 if this is a primary key index. The same logic applies to unique, 1 for unique fields. Also note that since unique is a reserved word, we had to enclose it in brackets in order to use it in our query. 
That just leaves the ordinal_position, which has the same use here as it did in the columns view in yesterday’s post. It indicates the order the fields occur in the index.  
Indexes are pretty simple, but it’s handy to be able to determine what you have available. 

System Views in SQL Server Compact Edition: Columns

Today we’re going to explore a view that is quite a bit more useful. First though, I spent a little time rewriting the create table scripts so we could fully explore a lot of the features these tables and SSCE has to offer.

Drop the two tables you created yesterday, or just create a new database. Then you can run these statements:

create table employee (
empid uniqueidentifier not null,
last   nvarchar(100),
first nvarchar(100),
birth  datetime,
constraint pk_empid primary key (empid)
);
 
create table parts (
partid bigint IDENTITY(100,1) not null,
partname nvarchar(100) not null,
qtyonhand int default 0,
constraint pk_parts primary key (partid)
);
 
create table inventory (
partid bigint not null,
binid bigint not null,
location nvarchar(50),
constraint pk_inventory primary key (partid, binid),
constraint fk_part foreign key (partid) references parts(partid)
);
 
As you can see, the new version of parts uses a bigint for the primary key, and I’ve set it up as an identity column. The 100, 1 after identity tells SSCE to start the first number at 100, and increment by 1. 
For use in a later example I’ve also redone the inventory table and added a part table. I’ve made the index for the inventory table two parts, and added a foreign key back to the parts table. Now let’s take a look at the Columns view.  
Like many of the views, a simple select * is going to return a lot of empty fields. Thus I have created the following statement which returns the most useful fields to us.  

select table_name, column_name, ordinal_position, 
       column_hasdefault, column_flags, is_nullable, data_type,
       character_maximum_length, numeric_precision, numeric_scale, 
       datetime_precision, autoinc_min, autoinc_max, autoinc_next, 
       autoinc_seed, autoinc_increment
  from information_schema.columns
 
I won’t go over every single field, but let me point out a few of the more useful ones. The table_name, column_name, and data_type fields are pretty obvious and are probably the ones you’ll use the most. 
Column_hasdefault is a Boolean, 1 indicates there’s a default value, 0 indicates there’s no default. Character_maximum_length is just as it describes, for character types it indicates the max length, for non characters it will be null.  
The autoinc_* fields are only valid for ints or bigints being used as identity columns, such as the partid field in the parts table. Min and max are obvious, describe the bounds of the field. Seed simply shows what the starting value is. This can be handy if you want to know what value to start reading from. Increment shows the value to add when creating the next primary key.  
The most handy though is Next. Next will show you what the next primary key will be. This can be useful if the user is creating a new record, and you’d like to go ahead and show them what the new primary key will be without wanting to create the record.  
Finally is ordinal_position. This field indicates the order the fields occur in the table. Use this for sorting, if you want to display the fields in the same order as the database: order by ordinal_position. 

System Views in SQL Server Compact Edition: Tables

First off, let me say a few thank you’s. Thanks to the Lower Alabama .Net User Group for putting on a great code camp. And thanks to all of you who attended my presentation, I felt honored, especially considering some of the others who were speaking at the same time. Now, on to the views.

While SQL Server Compact Edition does not support the creation of views, it does come with several views built in. For those of you familiar with full blown SQL Server, these will be familiar as they are all part of the INFORMATION_SCHEMA.

There are seven, Columns, Indexes, Key_Column_Usage, Tables, Table_Constraints, Provider_Types, and Referential_Constraints. When SSCE was created, these views were setup to mimic many of the views of “big” SQL Server. But because SSCE only supports a limited set of features, many of the fields wind up being NULL. Like in the INFORMATION_SCHEMA.TABLES view.

For this example, I’m creating a couple of very simple tables. Start by creating a brand new SSCE database. Next, here’s the SQL needed to create my example tables, you should be able to use either Visual Studio Database Explorer or SQL Server Management Studio.

create table employee (
empid uniqueidentifier not null,
last   nvarchar(100),
first nvarchar(100),
birth  datetime,
constraint pk_empid primary key (empid)
);
go
create table inventory (
partid uniqueidentifier not null,
partname nvarchar(100) not null,
qtyonhand int,
location nvarchar(50),
constraint pk_partid primary key (partid)
)

OK, now that you have a few tables created, let’s issue the following command:

select * from information_schema.tables;

What gets brought back is:

You’ll note all the NULLs, as I said most of this was jettisoned in order to put the Compact in Compact Edition. As such, we have a lot of unnecessary fields in the output. Let’s refine the query a little:

select table_name, table_type from information_schema.tables;

Produces this output:

At first glance you may think the TABLE_TYPE of TABLE is redundant. And with the state of SSCE today you’d be right. But for the time being if you want to write queries that will survive into the future, I’d suggest writing your SQL as:

select table_name from information_schema.tables where table_type = ‘TABLE’;

This will give you this output:

Now you have a nice, safe query that will return all table names in your database, and you can rest assured that it will survive into the future should Microsoft decide to add other object types to the Tables view.

So what could you do with this? Well I setup a little test harness similar to the one I did in the last series. I created a simple windows form with one button named Tables and a label we’ll call lblResults. I also made a few other minor changes from my previous code base. Here’s the code, so you can see:

    // Class level to hold connection
    SqlCeConnection _cn = new SqlCeConnection(ConnectString()); 
 
    public Form1()
    {
      InitializeComponent();
    }
    #region ConnectString
    // This became static so it could be called 
    // during the constructor, so we could set the
    // class level variable.
    private static string ConnectString()
    {
      string connectionString;
      string fileName = “SSCE_View_Test.sdf”;
 
      connectionString = string.Format(
        “DataSource=\”{0}\” “, fileName) ; 
 
      return connectionString;
    }
    #endregion
 
    #region OpenConnection
    private void OpenConnection()
    {
      if (_cn.State==ConnectionState.Closed)
      {
        _cn.Open();
      }
 
    }
    #endregion
 
    #region btnTables_Click
    private void btnTables_Click(object sender, EventArgs e)
    {
      // In case it’s not already open
      // Calling it too much won’t hurt, 
      // as it checks first before trying
      OpenConnection();
 
      SqlCeCommand cmd;
      string sql = “select table_name “
      + “from information_schema.tables “
      + “where table_type = ‘TABLE'”;
 
      try
      {
        cmd = new SqlCeCommand(sql, _cn);
        cmd.CommandType = CommandType.Text;
        SqlCeResultSet rs = 
          cmd.ExecuteResultSet(ResultSetOptions.Scrollable);
 
        if (rs.HasRows)
        {
          int ordTable = rs.GetOrdinal(“table_name”);
          StringBuilder output = new StringBuilder();
          rs.ReadFirst();
          output.AppendLine(rs.GetString(ordTable));
          while (rs.Read())
          {
            output.AppendLine(rs.GetString(ordTable));
          }
          lblResults.Text = output.ToString();
        }
        else
          lblResults.Text = “No tables found.”;
      }
      catch (SqlCeException sqlexception)
      {
        MessageBox.Show(sqlexception.Message, “Oh Crap.”,
          MessageBoxButtons.OK, MessageBoxIcon.Error);
      }
      catch (Exception ex)
      {
        MessageBox.Show(ex.Message, “Oh Crap.”,
          MessageBoxButtons.OK, MessageBoxIcon.Error);
      }
 
    }
    #endregion
  }
 
Here’s the output:
 
 
You could use this to build your own SQL Queries, reports, or to do code generation. 
The rest of the examples in this series will fall into the same test harness, so be sure to get a good look and understanding. The rest of the week we’ll spend exploring some of the more useful SSCE Views. 

Alabama Code Camp Slides

Here’s a copy of the Slides I’ll be using (or used depending on when you read this) at Alabama Code Camp 4 in Mobile AL. They are in PDF format.

Getting Started with SQL Server Compact Edition – Code Camp Slides

Thanks to all who came to my presentation!

SQL Server Compact Edition with C# and VB.Net

As a wrap up before this weekend’s code camp (http://alabamacodecamp.com), I wanted to upload the entire project so you could have it in one spot. In addition, I’ve also created a VB.Net version. I won’t go back over and comment on everything, you can look over the posts from my last few days for detailed explanations this is simply so you can have the code all in one spot.

I did the project as a simple windows project, here is an example of what my final form looked like:

The C# version of the form looked identical except in the title bar, which reads SSCE C# Version.

Here is the complete C# version of the code behind the form. Note there is one difference from the code I put in my previous blog posts, in the LoadARow method I had the parameters in the order of last name, then first name, but in the tnLoadTable_Click when I called LoadARow I had put the cool people’s names in the order of first name, last name. I fixed that in the version below.

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Text;

using System.Windows.Forms;

using System.Data.SqlServerCe;

using System.IO;

namespace SSCE1

{

public partial class Form1 : Form

{

#region Form1

public Form1()

{

InitializeComponent();

}

#endregion

#region btnCreateDatabase_Click

private void btnCreateDatabase_Click(object sender, EventArgs e)

{

string connectionString;

string fileName = “ArcaneCode.sdf”;

string password = “arcanecode”;

if (File.Exists(fileName))

{

File.Delete(fileName);

}

connectionString = string.Format(

“DataSource=\”{0}\”; Password='{1}'”, fileName, password);

SqlCeEngine en = new SqlCeEngine(connectionString);

en.CreateDatabase();

lblResults.Text = “Database Created.”;

}

#endregion

#region btnCreateTable_Click

private void btnCreateTable_Click(object sender, EventArgs e)

{

SqlCeConnection cn = new SqlCeConnection(ConnectString());

if (cn.State==ConnectionState.Closed)

{

cn.Open();

}

SqlCeCommand cmd;

string sql = “create table CoolPeople (“

+ “LastName nvarchar (40) not null, “

+ “FirstName nvarchar (40), “

+ “URL nvarchar (256) )”;

cmd = new SqlCeCommand(sql, cn);

try

{

cmd.ExecuteNonQuery();

lblResults.Text = “Table Created.”;

}

catch (SqlCeException sqlexception)

{

MessageBox.Show(sqlexception.Message, “Oh Crap.”, MessageBoxButtons.OK, MessageBoxIcon.Error);

}

catch (Exception ex)

{

MessageBox.Show(ex.Message, “Oh Crap.”, MessageBoxButtons.OK, MessageBoxIcon.Error);

}

finally

{

cn.Close();

}

#endregion

#region ConnectString

private string ConnectString()

{

string connectionString;

string fileName = “ArcaneCode.sdf”;

string password = “arcanecode”;

connectionString = string.Format(

“DataSource=\”{0}\”; Password='{1}'”, fileName, password);

return connectionString;

}

#endregion

#region btnLoadTable_Click

private void btnLoadTable_Click(object sender, EventArgs e)

{

try

{

LoadARow(“Carl”, “Franklin”, @”http:\\www.dnrtv.com”);

LoadARow(“Richard”, “Campbell”, @”http:\\www.dotnetrocks.com”);

LoadARow(“Leo”, “Laporte”, @”http:\\www.twit.tv”);

LoadARow(“Steve”, “Gibson”, @”http:\\www.grc.com”);

LoadARow(“Arcane”, “Code”, @”http:\\arcanecode.wordpress.com”);

}

catch (Exception ex)

{

MessageBox.Show(ex.Message, “Oh Crap.”, MessageBoxButtons.OK, MessageBoxIcon.Error);

}

#endregion

#region LoadARow

private void LoadARow(string first, string last, string url)

{

SqlCeConnection cn = new SqlCeConnection(ConnectString());

if (cn.State == ConnectionState.Closed)

{

cn.Open();

}

SqlCeCommand cmd;

string sql = “insert into CoolPeople “

+ “(LastName, FirstName, URL) “

+ “values (@lastname, @firstname, @url)”;

try

{

cmd = new SqlCeCommand(sql, cn);

cmd.Parameters.AddWithValue(“@lastname”, last);

cmd.Parameters.AddWithValue(“@firstname”, first);

cmd.Parameters.AddWithValue(“@url”, url);

cmd.ExecuteNonQuery();

lblResults.Text = “Row Added.”;

}

catch (SqlCeException sqlexception)

{

MessageBox.Show(sqlexception.Message, “Oh Crap.”, MessageBoxButtons.OK, MessageBoxIcon.Error);

}

catch (Exception ex)

{

MessageBox.Show(ex.Message, “Oh Crap.”, MessageBoxButtons.OK, MessageBoxIcon.Error);

}

finally

{

cn.Close();

}

#endregion

#region cmdLoadDataGrid_Click

private void cmdLoadDataGrid_Click(object sender, EventArgs e)

{

SqlCeConnection cn = new SqlCeConnection(ConnectString());

if (cn.State==ConnectionState.Closed)

{

cn.Open();

}

try

{

// Set the command to use the table, not a query

SqlCeCommand cmd = new SqlCeCommand(“CoolPeople”, cn);

cmd.CommandType = CommandType.TableDirect;

// Get the table

SqlCeResultSet rs = cmd.ExecuteResultSet(

ResultSetOptions.Scrollable);

// load the result set into the datasource

dgvCoolPeople.DataSource = rs;

}

catch (SqlCeException sqlexception)

{

MessageBox.Show(sqlexception.Message, “Oh Crap.”,

MessageBoxButtons.OK, MessageBoxIcon.Error);

}

catch (Exception ex)

{

MessageBox.Show(ex.Message, “Oh Crap.”,

MessageBoxButtons.OK, MessageBoxIcon.Error);

}

// Note, do not close the connection,

// if you do the grid won’t be able to display.

// For production code you probably want to make

// your result set (rs) a class level variable

}

#endregion

#region btnReadRecords_Click

private void btnReadRecords_Click(object sender, EventArgs e)

{

SqlCeConnection cn = new SqlCeConnection(ConnectString());

if (cn.State == ConnectionState.Closed)

{

cn.Open();

}

// Build the sql query. If this was real life,

// I’d use a parameter for the where bit

// to avoid SQL Injection attacks.

string sql = “select LastName, FirstName from CoolPeople “;

if (txtName.Text.Length > 0)

{

sql += “where LastName like ‘” + txtName.Text + “%’ “;

}

try

{

SqlCeCommand cmd = new SqlCeCommand(sql, cn);

cmd.CommandType = CommandType.Text;

// if you don’t set the result set to

// scrollable HasRows does not work

SqlCeResultSet rs = cmd.ExecuteResultSet(

ResultSetOptions.Scrollable);

// If you need to be able to update the result set, instead use:

// SqlCeResultSet rs = cmd.ExecuteResultSet(

// ResultSetOptions.Scrollable | ResultSetOptions.Updatable);

if (rs.HasRows)

{

// Use the get ordinal function so you don’t

// have to worry about remembering what

// order your SQL put the field names in.

int ordLastName = rs.GetOrdinal(“LastName”);

int ordFirstname = rs.GetOrdinal(“FirstName”);

// Hold the output

StringBuilder output = new StringBuilder();

// Read the first record and get it’s data

rs.ReadFirst();

output.AppendLine(rs.GetString(ordFirstname)

+ ” “ + rs.GetString(ordLastName));

// Now read thru the rest of the records.

// When there’s no more data, .Read returns false.

while (rs.Read())

{

output.AppendLine(rs.GetString(ordFirstname)

+ ” “ + rs.GetString(ordLastName));

}

// Set the output in the label

lblResults.Text = output.ToString();

}

else

{

lblResults.Text = “No Rows Found.”;

}

catch (SqlCeException sqlexception)

{

MessageBox.Show(sqlexception.Message, “Oh Crap.”,

MessageBoxButtons.OK, MessageBoxIcon.Error);

}

catch (Exception ex)

{

MessageBox.Show(ex.Message, “Oh Crap.”,

MessageBoxButtons.OK, MessageBoxIcon.Error);

}

finally

{

// Don’t need it anymore so we’ll be good and close it.

// in a ‘real life’ situation

// cn would likely be class level

cn.Close();

}

#endregion

}

Here is the VB.Net version of the code. I tried to make all of the method names, variable names and comments match the C# version as much as possible.

Imports System

Imports System.Collections.Generic

Imports System.ComponentModel

Imports System.Data

Imports System.Drawing

Imports System.Text

Imports System.Windows.Forms

Imports System.Data.SqlServerCe

Imports System.IO

Public Class Form1

#Region “btnCreateDatabase_Click”

‘ Create an empty SSCE Database with a password.

‘ Note that when creating a db with code, adding a

‘ password automatically encrypts the database

Private Sub btnCreateDatabase_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) Handles btnCreateDatabase.Click

Dim connectString As String = “”

Dim fileName As String = “ArcaneCode.sdf”

Dim password As String = “arcanecode”

If File.Exists(fileName) Then

File.Delete(fileName)

End If

connectString = String.Format( _

“DataSource=””{0}””; Password='{1}'”, fileName, password)

Dim eng As SqlCeEngine = _

New SqlCeEngine(connectString)

eng.CreateDatabase()

lblResults.Text = “Database Created”

End Sub

#End Region

#Region “btnCreateTable_Click”

‘ Issue a SQL command to create a table

‘ Note this only creates the table, it

‘ does not put any rows in it.

Private Sub btnCreateTable_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) Handles btnCreateTable.Click

Dim cn As New SqlCeConnection(ConnectString())

If cn.State = ConnectionState.Closed Then

cn.Open()

End If

Dim cmd As SqlCeCommand

Dim sql As String = “create table CoolPeople (“ _

+ “LastName nvarchar (40) not null, “ _

+ “FirstName nvarchar (40), “ _

+ “URL nvarchar (256) )”

cmd = New SqlCeCommand(sql, cn)

Try

cmd.ExecuteNonQuery()

lblResults.Text = “Table created.”

Catch sqlexception As SqlCeException

MessageBox.Show(sqlexception.Message, “Oh Crap.” _

, MessageBoxButtons.OK, MessageBoxIcon.Error)

Catch ex As Exception

MessageBox.Show(ex.Message, “Oh Crap.” _

, MessageBoxButtons.OK, MessageBoxIcon.Error)

Finally

cn.Close()

End Try

End Sub

#End Region

#Region “btnLoadTable_Click”

‘ This routine calls a subroutine that

‘ does the real work of inserting rows

‘ into the database.

Private Sub btnLoadTable_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) Handles btnLoadTable.Click

Try

LoadARow(“Scott”, “Hanselman”, “http:\\www.hanselminutes.com”)

LoadARow(“Wally”, “McClure”, “http:\\aspnetpodcast.com/CS11/Default.aspx”)

LoadARow(“John”, “Dvorak”, “http:\\www.crankygeeks.com”)

LoadARow(“Arcane”, “Code”, “http:\\arcanecode.wordpress.com”)

Catch ex As Exception

MessageBox.Show(ex.Message, “Oh Crap.”, _

MessageBoxButtons.OK, MessageBoxIcon.Error)

End Try

End Sub

#End Region

#Region “ConnectString”

‘ A central place to serve up the connection string

Private Function ConnectString() As String

Dim connectionString As String

Dim fileName As String = “ArcaneCode.sdf”

Dim password As String = “arcanecode”

connectionString = String.Format( _

“DataSource=””{0}””; Password='{1}'”, fileName, password)

Return connectionString

End Function

#End Region

#Region “LoadARow”

‘ Generates the SQL and issues the command to

‘ insert a single row into the database

Private Sub LoadARow(ByVal first As String, _

ByVal last As String, ByVal url As String)

Dim cn As New SqlCeConnection(ConnectString())

If cn.State = ConnectionState.Closed Then

cn.Open()

End If

Dim cmd As SqlCeCommand

Dim sql As String = “insert into CoolPeople “ _

+ “(LastName, FirstName, URL) “ _

+ “values (@lastname, @firstname, @url)”

Try

cmd = New SqlCeCommand(sql, cn)

cmd.Parameters.AddWithValue(“@lastname”, last)

cmd.Parameters.AddWithValue(“@firstname”, first)

cmd.Parameters.AddWithValue(“@url”, url)

cmd.ExecuteNonQuery()

lblResults.Text = “Row Added.”

Catch sqlexception As SqlCeException

MessageBox.Show(sqlexception.Message, “Oh Crap.”, _

MessageBoxButtons.OK, MessageBoxIcon.Error)

Catch ex As Exception

MessageBox.Show(ex.Message, “Oh Crap.”, _

MessageBoxButtons.OK, MessageBoxIcon.Error)

Finally

cn.Close()

End Try

End Sub

#End Region

#Region “btnLoadGrid_Click”

Private Sub btnLoadGrid_Click(ByVal sender As System.Object _

, ByVal e As System.EventArgs) Handles btnLoadGrid.Click

Dim cn As New SqlCeConnection(ConnectString())

If cn.State = ConnectionState.Closed Then

cn.Open()

End If

Try

‘ Set the command to use the table, not a query

Dim cmd As SqlCeCommand = New SqlCeCommand(“CoolPeople”, cn)

cmd.CommandType = CommandType.TableDirect

‘ Get the Table

Dim rs As SqlCeResultSet = cmd.ExecuteResultSet( _

ResultSetOptions.Scrollable)

‘ Load the result set into the database

dgvCoolPeople.DataSource = rs

Catch sqlexception As SqlCeException

MessageBox.Show(sqlexception.Message, “Oh Crap.”, _

MessageBoxButtons.OK, MessageBoxIcon.Error)

Catch ex As Exception

MessageBox.Show(ex.Message, “Oh Crap.”, _

MessageBoxButtons.OK, MessageBoxIcon.Error)

End Try

‘ Note, do not close the connection,

‘ if you do the grid won’t be able to display.

‘ For production code you probably want to make

‘ your result set (rs) a class level variable

End Sub

#End Region

#Region “btnReadRecords_Click”

Private Sub btnReadRecords_Click(ByVal sender As System.Object _

, ByVal e As System.EventArgs) Handles btnReadRecords.Click

Dim cn As New SqlCeConnection(ConnectString())

If cn.State = ConnectionState.Closed Then

cn.Open()

End If

‘ Build the sql query. If this was real life,

‘ I’d use a parameter for the where bit

‘ to avoid SQL Injection attacks.

Dim sql As String = “select LastName, FirstName from CoolPeople “

If txtName.Text.Length > 0 Then

sql += “where LastName like ‘” + txtName.Text + “%’ “

End If

Try

Dim cmd As SqlCeCommand = New SqlCeCommand(sql, cn)

cmd.CommandType = CommandType.Text

‘ if you don’t set the result set to

‘ scrollable HasRows does not work

Dim rs As SqlCeResultSet = cmd.ExecuteResultSet( _

ResultSetOptions.Scrollable)

If rs.HasRows Then

‘ Use the get ordinal function so you don’t

‘ have to worry about remembering what

‘ order your SQL put the field names in.

Dim ordLastName As Integer = rs.GetOrdinal(“LastName”)

Dim ordFirstName As Integer = rs.GetOrdinal(“FirstName”)

‘ Hold the output

Dim output As StringBuilder = New StringBuilder()

‘ Read the first record and get it’s data

rs.ReadFirst()

output.AppendLine(rs.GetString(ordFirstName) _

+ ” “ + rs.GetString(ordLastName))

‘ Now read thru the rest of the records.

‘ When there’s no more data, .Read returns false.

Do While rs.Read()

output.AppendLine(rs.GetString(ordFirstName) _

+ ” “ + rs.GetString(ordLastName))

Loop

‘ Set the output in the label

lblResults.Text = output.ToString()

Else

lblResults.Text = “No Rows Found.”

End If

Catch sqlexception As SqlCeException

MessageBox.Show(sqlexception.Message, “Oh Crap.”, _

MessageBoxButtons.OK, MessageBoxIcon.Error)

Catch ex As Exception

MessageBox.Show(ex.Message, “Oh Crap.”, _

MessageBoxButtons.OK, MessageBoxIcon.Error)

Finally

‘ Don’t need it anymore so we’ll be good and close it.

‘ in a ‘real life’ situation

‘ cn would likely be class level

cn.Close()

End Try

End Sub

#End Region

End Class

There you go, the complete sample project for working with SQL Server Compact Edition. If you found this useful, please post a comment and let us know what sorts of applications you build using SSCE.

Hope to see you at code camp!

Reading From A SQL Server Compact Edition Database With C#

In our discussions so far, I’ve shown how to create SSCE databases and load them with data. By now I’m sure you are wondering how to pull that data back out. Today I will show you two methods, first a way to bind the data to a control, then how to read through a tables rows programmatically.

First, create a form and put a button on, call it btnLoadGrid. Next add a data grid viewer control, I named mine dgvCoolPeople after the table we’ll be reading.

In the click event for the button, here’s the code you’ll need:

private void cmdLoadDataGrid_Click(object sender, EventArgs e)
    {
      SqlCeConnection cn = new SqlCeConnection(ConnectString());
 
      if (cn.State==ConnectionState.Closed)
      {
        cn.Open();
      }
 
      try
      {
        // Set the command to use the table, not a query
        SqlCeCommand cmd = new SqlCeCommand(“CoolPeople”, cn);
        cmd.CommandType = CommandType.TableDirect;
 
        // Get the table
        SqlCeResultSet rs = cmd.ExecuteResultSet(
          ResultSetOptions.Scrollable);
 
        // load the result set into the datasource
        dgvCoolPeople.DataSource = rs;
      }
      catch (SqlCeException sqlexception)
      {
        MessageBox.Show(sqlexception.Message, “Oh Crap.”, 
          MessageBoxButtons.OK, MessageBoxIcon.Error);
      }
      catch (Exception ex)
      {
        MessageBox.Show(ex.Message, “Oh Crap.”, 
          MessageBoxButtons.OK, MessageBoxIcon.Error);
      }
 
      // Note, do not close the connection, 
      // if you do the grid won’t be able to display.
      // For production code you probably want to make 
      // your result set (rs) a class level variable
 
    }
 
First we open the database, as you have seen before. Next we set the command to a new SqlCeCommand, and pass in the name of the table, CoolPeople. Then we tell the command it’s type is TableDirect. Using this method we can directly access the table, which is very fast if we are doing a quick read through all rows. 
Next we execute the command and return a SqlCeResultSet, which is then loaded into the data source for the dgvCoolPeople grid viewer control.  
The one important thing to note is NOT to close the connection, otherwise it will also close your grid. Normally I would keep my connection at the class level instead of in a method.  
And that’s all there is to it, I should mention if you want your grid updateable make sure to use ResultSetOptions.Scrollable|ResultSetOptions.Updatable in the ExecuteResultSet method.  
Now that you’ve seen how to bind your control, let’s look at what it takes to step through the rows programmatically. Go back to your form and add another button, call it btnReadRecords. Also add a textbox named txtName. Finally if you are using your code from before, you already have a label named lblResult, if not go ahead and add it as well.  

    private void btnReadRecords_Click(object sender, EventArgs e)
    {
      SqlCeConnection cn = new SqlCeConnection(ConnectString());
 
      if (cn.State == ConnectionState.Closed)
      {
        cn.Open();
      }
 
      // Build the sql query. If this was real life,
      // I’d use a parameter for the where bit
      // to avoid SQL Injection attacks. 
      string sql = “select LastName, FirstName from CoolPeople “;
      if (txtName.Text.Length > 0)
      {
        sql += “where LastName like ‘” + txtName.Text + “%’ “;
      }
 
      try
      {
        SqlCeCommand cmd = new SqlCeCommand(sql, cn);
        cmd.CommandType = CommandType.Text;
 
        // if you don’t set the result set to 
        // scrollable HasRows does not work
        SqlCeResultSet rs = cmd.ExecuteResultSet(
          ResultSetOptions.Scrollable);
 
        // If you need to be able to update the result set, instead use:
        // SqlCeResultSet rs = cmd.ExecuteResultSet(
        //  ResultSetOptions.Scrollable | ResultSetOptions.Updatable);
 
        if (rs.HasRows)
        {
          // Use the get ordinal function so you don’t 
          // have to worry about remembering what 
          // order your SQL put the field names in. 
          int ordLastName = rs.GetOrdinal(“LastName”);
          int ordFirstname = rs.GetOrdinal(“FirstName”);
 
          // Hold the output
          StringBuilder output = new StringBuilder();
 
          // Read the first record and get it’s data
          rs.ReadFirst();
          output.AppendLine(rs.GetString(ordFirstname) 
            + ” “ + rs.GetString(ordLastName));
 
          // Now read thru the rest of the records.
          // When there’s no more data, .Read returns false.
          while (rs.Read())
          {
            output.AppendLine(rs.GetString(ordFirstname) 
              + ” “ + rs.GetString(ordLastName));
          }
 
          // Set the output in the label
          lblResults.Text = output.ToString();
        }
        else
        {
          lblResults.Text = “No Rows Found.”;
        }
 
      }
      catch (SqlCeException sqlexception)
      {
        MessageBox.Show(sqlexception.Message, “Oh Crap.”, 
          MessageBoxButtons.OK, MessageBoxIcon.Error);
      }
      catch (Exception ex)
      {
        MessageBox.Show(ex.Message, “Oh Crap.”, 
          MessageBoxButtons.OK, MessageBoxIcon.Error);
      }
      finally
      {
        // Don’t need it anymore so we’ll be good and close it.
        // in a ‘real life’ situation 
        // cn would likely be class level
        cn.Close(); 
      }
 
    }
 
Again we open the connection, then setup our SQL statement. This time I’ve constructed a simple select. If the user enters a letter for a name, I’ve added code for an optional where clause to limit the number of rows returned. 
Like with the grid, we need to create a command that we can execute. This time we’ll pass in the SQL statement, and indicate that it is a SQL Statement by setting the command type to text.  
Let me take a short side trip, if you typed in the code, when you hit the period after “CommandType”, you should have noticed 3 options.. The first two we have discussed, TableDirect and Text. You’ll also notice there’s a choice for “StoredProcedure”.  
If you read the previous articles, you’ll probably be scratching your head as I’ve already said SSCE does not support stored procedures. So why is this option in the list?  
Ya got me. My guess is they are sharing the intellisense with another library, and didn’t or couldn’t remove it. Either way, you should ignore it. If you try to use it all you’ll do is generate a run time error.  
Back to the code, you see the next thing that is done is a check for HasRows. I need to emphasize something very important: HasRows only works when the Scrollable option is set in the ExecuteResultSet method! I can’t tell you why, I can just tell you to make sure to use a scrollable option or else you’ll have no end of headaches.  
So if we have rows, we obviously want to process them. To retrieve column data from a SSCE row, the SqlCeResultSet object has a variety of GetType methods, where Type is such things as String or Int. In order to make it work, you pass the GetType methods what they call an ordinal value, which is nothing more than an integer that indicates the column number you want to retrieve. 
I, for one don’t want to have to keep up with which column is which number, further I want the flexibility to change my column order or add new columns without worrying about a lot of code refactoring. That’s where the GetOrdinal method comes into play. 
Simply call GetOrdinal and pass in a string with the name of the column, and SSCE will tell you what column number it’s in. Because I use these several times I took these and stored them in int variables. Now I’m free to go change my SQL all I want and don’t have to worry about breaking the rest of my code. It’s a technique I highly advise you to follow.  
OK, so we know which column goes where, from here it’s pretty simple. Use the ReadFirst method to move to the first row, then let’s grab it’s data using the GetString methods. 
Next we enter a while loop, the Read method will move us to the next record, and return false when there are no more records (thus exiting the loop).  
And finally we copy the output we’ve been building into the label control. In this case I have no more need for the connection, so unlike in the grid example I can go ahead and close this connection variable.  
These two techniques can be interchanged, for example I could have used a table direct to load my label, or a text type command to load the grid view. But these two basic techniques should give you all the functionality to complete your toolset for working with SSCE databases.  
 

Create a SQL Server Compact Edition Database Using SQL Server 2005 Management Studio

Yesterday I showed you how to create a SQL Server Compact Edition database, using Visual Studio. Today I’ll show you how to create the same database using SQL Server 2005 Management Studio.

When you launch SQL Server Management Studio, you are shown the normal “Connect to Server” dialog. First, you need to change the Server Type to “SQL Server Compact Edition”. Now in the Database File area, click on the drop down and pick “<New Database…>”.

After picking the new database option, you should see a familiar looking dialog. Enter the name for your database, or browse for it. Like I said yesterday, I always encrypt and use a password, if you want to as well check Encrypt on and enter a password. Remember if you do choose to encrypt, you must enter a password.

Like yesterday, if you use a weak password you are warned. Either click no and enter a stronger password or click Yes to continue.

Now your database has been created, and you are brought back to the original “Connect to Server” dialog you saw. SQL Server Management Studio has helpfully filled in the Database File name for you as well as the password. I clicked “Remember Password” on then clicked the Connect button.

You are now brought to the standard SQL Server Management Studio interface.

From here on, you’ll find things work almost identically to Visual Studio. If you right click on the Tables, you’ll see the same menu. If you pick “New Table” you will see the same dialog as yesterday. Rather than repeating myself, I’ll suggest you take a look at yesterday’s blog entry for more details on creating tables and adding rows.

I can hear the questions now: Why would you use SQL Server Management Studio over Visual Studio to create and manage your SSCE database?

It really comes down to a matter of your viewpoint. If you are a long time developer, you will be more comfortable with Visual Studio and thus want to use it to handle your SSCE database. On the other hand, if you are a DBA and have been assigned the task of managing the SSCE databases, you will be more familiar with management studio and thus want to use it as your tool of choice.

So there you go, yet another way to create a SQL Server Compact Edition database. Which tool you use is up to you!

Creating a SQL Server Compact Edition Database Using Visual Studio Server Explorer

In the past I showed how to create a new SQL Server Compact Edition (SSCE) database using code. While it’s great for your app to be able to be able to create its own database(s), it’s not always necessary. For example, if you will be deploying the database with your app, it’s not really necessary to write the code to create it.

Instead, you can create the SSCE database right from within Visual Studio 2005. First, if Server Explorer is not visible select View, Server Explorer from the menu. Now right Click on Data Connections, and pick “Add Connection…”.

Note do NOT pick the Create New SQL Server Database… option, this works with full blown SQL Server such as SQL Server Express, not SSCE.

On the next screen, make sure the Data source is set to the “Microsoft SQL Server 2005 Compact Edition (.NET Framework Data Provider for SQL Server CE)”, if not click the Change button to launch a dialog where you can select it.

For Data Source make sure My Computer is picked, then enter the directory and path where you want your database stored. Note SSCE databases need to end with a .SDF extension (case is unimportant, .sdf works just as well).

Next is the password. I always create my databases with a password. It makes them more secure, and adding a password will also allow you to encrypt the database to keep it safe from prying eyes. However, you can select not to do so if you want.

Now you’ve got everything filled out, just click the “Create” button.

A new dialog will appear. Note this is your chance to encrypt the database, as I mentioned I always click this ON. Now click OK.

Note if you use a very simple password, as I did for this example (I picked arcanecode as the password) you may get an error dialog.

What it’s simply letting you know is that your password is not very secure. If this were a production system I would absolutely click No, and go enter a much more complex password. I entered a weak password for this demo so I could show you the dialog, so to move things along I’ll click Yes to continue with the password I entered.

You’ll note you’ve been returned to the Add Connection dialog. Let’s see if the create was successful. Click the Test Connection button. If all went well you will see the “Test connection succeeded” message. Click OK to continue.

Returning to the Server Explorer, your new database (which I named ArcaneCode2) should be listed in your Data Connections tree. Click the + button to expand, and you can see the Tables, System Views (not to be confused with a traditional database view), and a Replication folder.

Note that if you wanted to open an existing SSCE database, you’d simply skip the steps associated with the Create button. Instead you’d simply pick “Add Connection…”, key in (or browse for) the database name, enter the password and click Open.

Let’s create a new table. Right click on the Tables and select Create Table.

In the dialog that appears, key in some standard info for your table.

In this example, I named the table CodeCampAttendees, with the column ccaID being the unique ID. One thing I generally do is to use a system generated ID as a behind the scenes unique ID for a row in my databases. In some rare circumstances I’m comfortable using some intelligent key, but in most cases I prefer the computer generate me a key, and I’ll keep up with it behind the scenes (never, and I mean never show these to the user, they’ll abuse the heck out of it).

That said, what are your choices when it comes to unique ID’s? You have two, first is the uniqueidentifier data type, which is a GUID. I like GUIDs, but the one drawback they have is that SSCE won’t automatically generate one for you, you have to take care of that yourself.

The second choice is to use an Int or BigInt. Then in the properties area under the column editor, for the ccaID column change the Identity property to True. This will result in an new ID being generated for you everytime you insert a row. You can also fine tune by setting the value with which the IDs will be incremented on each insert (IdentityIncrement) and what you want the first value to be (IdentitySeed). Often rather than starting with “1”, people will prefer to start with a larger number such as 10000 so the numbers will look more uniform as they increment.

For this example, I’ve picked a BigInt, set the Identity property to true, and Primary Key true for the ccaID column, then entered my remaining columns as nvarchars.

Once you have entered all the fields you want, click OK. Drilling down into our new table, you can see all the columns that were entered. In addition, when I created the table I picked ccaID as my Primary Key, and you can see an Index was automatically created for us.

Finally we can even add a few rows, simply right click on the table name and pick “Open”. You can view, alter, delete or add new records. Here you can see I added a few new rows, note I did not enter the ccaID. SQL Server Compact Edition took care of that for me.

You can also do other standard table maintenance via Visual Studio, such as altering the table schema or dropping the table all together. One of the coolest things is the query creator.

Right click on the table name, and pick New Query, then pick the table name(s) from the next dialog. Now you’ll see a dialog that looks disturbingly like the old Access dialog for creating queries. I won’t go into details on how to use it here, but thought you’d like quick screen shot:

There’s not much more I can say here, this pretty much covers the major features surrounding table creation in SQL Server Compact Edition. Note many of the features will work with any database. Once you make a connection, you can use all the features I’ve shown here to maintain your database whether it’s in SQL Server, SSCE, or even Oracle (assuming you have permissions of course!).