When you create a parameterized command against Microsoft
SQL Server 7.0, if you call the Prepare
method before you add parameters to the command, you receive the
following error message:
An unhandled exception of type
'System.Data.SqlClient.SqlException' occurred in system.data.dll.
Additional information: System error.
This problem does not occur in
SQL Server 2000.
This problem occurs in SQL Server 7.0 because, by design,
you cannot run the Prepare
method before you add parameters. This applies to most database
SQL Server 2000 does not generate the above-mentioned
exception because it does not run Prepare
until the first command is executed. This optimization prevents
the overhead of Prepare
if no commands are subsequently executed.
To resolve this problem, do not call the Prepare
method until after you add the parameters.
Steps to reproduce the behavior
The sample code to follow uses the Region table of the Northwind
- Start Microsoft Visual Studio .NET.
- Create a new Windows Application project in Visual C# .NET.
Form1 is added to the project by default.
- Make sure that your project contains a reference to the System.Data namespace, and add a reference to this namespace if it does
- Place a Button control on Form1. Change the Name property of the button to btnTest, and
change the Text property to Test.
- Use the using statement on the required namespaces so that you are not required
to qualify declarations in those namespaces later in your code. Add the
following code to the General Declarations section of Form1:
- Add the following code in the Click event for the button (Test).
Note You will need to change User ID <username>
and password =<strong password> to the correct values before you run this
code. Be sure that User ID has the appropriate permissions to perform this
operation on the database.
String myConnString = "User ID=<username>;password=<strong password>;Initial Catalog=northwind;
int id = 25;
string desc = "myFirstRegion";
SqlConnection rConn = new SqlConnection(myConnString);
SqlCommand command = new SqlCommand("", rConn);
command.CommandText = "insert into Region (RegionID, RegionDescription)
values (@id, @desc)";
//SQL Server 7.0 throws an exception here.
//Comment the following line to resolve this problem against SQL Server 7.0.
//You can call Prepare after you set up commandtext and parameters.
command.Parameters.Value = id;
command.Parameters.Value = desc;
- Modify the Connection string (myConnString) as appropriate for your environment.
- Save your project. On the Debug menu, click Start to run your project.
- Click Test. If you are connected to a SQL Server 7.0 database, the code
generates the above-mentioned exception.
If you are connected to a
SQL Server 2000 database, the code runs properly, and the "Updated
Successfully" message box appears.
- To resolve this problem against SQL Server 7.0, comment out
the call to command.Prepare that precedes the code to add the parameters, and then run the
For more information on ADO.NET objects and syntax, refer
to the following Microsoft .NET Framework Software Development Kit (SDK)
Article ID: 311348 - Last Review: February 27, 2014 - Revision: 3.8
- Microsoft ADO.NET 2.0
- Microsoft ADO.NET 1.0
- Microsoft Visual C# .NET 2002 Standard Edition
- Microsoft Visual C# .NET 2003 Standard Edition
- Microsoft Visual C# 2005
- Microsoft SQL Server 7.0 Standard Edition
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