SqlCeParameter Bug?

I made the following post to microsoft.public.sqlserver.ce on August 17th.

The following SqlCeCommand throws an exception. Is this a bug or am I doing something wrong?

SqlCeCommand sqlCmd = sqlConn.CreateCommand();
sqlCmd.CommandText = String.Format("INSERT INTO {0} (UserId, VersionId, {1}, PropertyName, PropertyValue, PropertyValueType) VALUES (@userid, @versionid, @headercolumnval, @propertyname, @propertyvalue, @propertyvaluetype)", strTable, headerName);
String strValue = p.Value.ToString();
sqlCmd.Parameters.Add("@userid", SqlDbType.NVarChar, 255, "UserId").Value = Globals.UserId;
sqlCmd.Parameters.Add("@versionid", SqlDbType.BigInt, 8, "VersionId").Value = Globals.VersionId;
sqlCmd.Parameters.Add("@headercolumnval", SqlDbType.NVarChar, 255, headerName).Value = headerColumnValue;
sqlCmd.Parameters.Add("@propertyname", SqlDbType.NVarChar, 255, "PropertyName").Value = p.Key;
sqlCmd.Parameters.Add("@propertyvalue", SqlDbType.NVarChar, 4000, "PropertyValue").Value = strValue;
sqlCmd.Parameters.Add("@propertyvaluetype", SqlDbType.NVarChar, 255, "PropertyValueType").Value = p.Type.FullName;
sqlCmd.Transaction = sqlTransact;
sqlCmd.Prepare();
sqlCmd.ExecuteNonQuery();
sqlCmd.Dispose();

Throws the following exception at the sqlCmd.ExecuteNonQuery() line:

System.InvalidOperationException was unhandled
Message="@propertyvalue : String truncation: max=255, len=463, value="(removed for posting clarity)"."
StackTrace:
at System.Data.SqlServerCe.SqlCeCommand.FillParameterDataBindings()
at System.Data.SqlServerCe.SqlCeCommand.ExecuteCommandText()
at System.Data.SqlServerCe.SqlCeCommand.ExecuteCommand()
at System.Data.SqlServerCe.SqlCeCommand.ExecuteNonQuery()
at MyExperience.IO.DatabasePopulator.InsertProperty()
at MyExperience.IO.DatabasePopulator.ParseTriggers()
at MyExperience.IO.DatabasePopulator.Populate()
at MyExperience.MyExperienceFramework.Initialize()
at MyExperience.Application.MainForm.OnLoad()
at System.Windows.Forms.Form._SetVisibleNotify()
at System.Windows.Forms.Control.set_Visible()
at OpenNETCF.Windows.Forms.Application2.RunMessageLoop()
at OpenNETCF.Windows.Forms.Application2.Run()
at MyExperience.Application.Program.Main()

However, if I change the line:

sqlCmd.Parameters.Add("@propertyvalue", SqlDbType.NVarChar, 4000, "PropertyValue").Value = strValue;

to

sqlCmd.Parameters.Add("@propertyvalue", SqlDbType.NVarChar).Value = strValue;

no exception is thrown and, better yet, the full amount of data actually makes it into the database. That is, the value is not truncated to the 255 length that Sql somehow thinks exists as a constraint.

Note that my schema for this table looks like:

TableName:
TriggerProperties

Columns:
UserId (PK, nvarchar(255), not null)
VersionId (PK, nvarchar(255), not null)
TriggerName (PK, nvarchar(255), not null)
PropertyName (PK, nvarchar(255), not null)
PropertyValue (nvarchar(4000), not null)
PropertyValueType (nvarchar(255), not null)

I followed this post up with this one on August 18th:

Ah, it looks like SqlCeParameter forces the Size property to 255. That's strange given the fact that the docs say, as previously mentioned, that the nvarchar data type can range from 1 to 4000 characters.

However, bear in mind, that by simply avoiding setting the Size property (either via the constructor or the property itself) allows one to INSERT nvarchar data much larger than 255. In other words, it looks like this "bug" is at the parameter level and not database level.

This is the test code:

for (int i = 0; i <= 500; i+=100){ SqlCeParameter param = new SqlCeParameter("@Test", SqlDbType.NVarChar, i); Debug.WriteLine(i + ": " + param.Size);

//Just in case the property acts differently, set it and print again
param.Size = i;
Debug.WriteLine(i + ": " + param.Size);

}

prints:

0: 0
0: 0
100: 100
100: 100
200: 200
200: 200
300: 255
300: 255
400: 255
400: 255
500: 255
500: 255

Any input from MS (or MVPs) on this? I'm far from being a seasoned C# SQL developer so maybe I'm doing something wrong.

Unfortunately I haven't heard any substantive comments back on usenet from MS or otherwise. Anyone in the blogosphere have an idea?

Update 8/25/2006 @ 11:08PM: On August 21st, I e-mailed the SQL Server Everywhere team via their contact page about this issue. Here's what I said:

Not sure how appropriate it is to contact you about problems I'm experiencing with Sql Mobile 2005, but I thought I'd give this a shot. If this is the wrong venue of communication, just ignore this plead for help.

I'm having issues with the SqlCeParameter class, particularly with regards to how it handles setting the Size property. I can't seem to set the size to anything larger than 255 for the nvarchar datatype.

Please see my usenet post for more details (unfortunately no one with any expertise in this area has responded yet): direct link here

I received a response on August 24th:

Yes Jon you are right that there seems to be some problem with larger than 255 chars. I just tried and could repro it.

I shall come back to you on this after some more digging around to see if there is any work around.

To which I responded:

Thank you so much for the response. I was really hoping I'd hear back from someone at Microsoft to help me with this.

The work around that I've come up with is to simply leave out specifying the length parameter in the SqlCeParameter object. So, for my SQL data columns that are of type nvarchar and length > 255 I do this:

SqlCeParameter param = new SqlCeParameter("@custid", SqlDbType.NVarChar);

Rather than explicitly including a length and column:

SqlCeParameter param = new SqlCeParameter("@custid", SqlDbType.NVarChar, 2000, “CustomerID”);

You’ll note that in the former case your data can be of length > 255 and, critically, it will still make it into the database. In the latter case, however, you incur an exception.

Perhaps my workaround will shed some light on the underlying problem.

On August 25th I received another response:

I found the work around you used works perfectly and some of the internal apps also use it the same way as you mentioned. However, while digging I found that you can not use parameterized query when you have image/ntext columns (Large Object Datatype). Will update you more once I get some clarity.

To which I responded:

Hmm, I also use image data types in my SQL Mobile 2005 database and it appears to be working. In fact, a parameterized query, I believe, is the only way to get binary data into the database. What was the issue you ran into here?