Creates a prepared version of the command on an instance of SQL Server.
Namespace: System.Data.SqlClient
Assembly: System.Data (in system.data.dll)
Visual Basic (Declaration)
Public Overrides Sub Prepare
Dim instance As SqlCommand
instance.Prepare
public override void Prepare ()
public:
virtual void Prepare () override
public override function Prepare ()
If CommandType is set to StoredProcedure, the call to Prepare should succeed, although it may cause a no-op.
Before you call Prepare, specify the data type of each parameter in the statement to be prepared. For each parameter that has a variable length data type, you must set the Size property to the maximum size needed. Prepare returns an error if these conditions are not met.
If you call an Execute method after calling Prepare, any parameter value that is larger than the value specified by the Size property is automatically truncated to the original specified size of the parameter, and no truncation errors are returned.
Output parameters (whether prepared or not) must have a user-specified data type. If you specify a variable length data type, you must also specify the maximum Size.
The following example demonstrates the use of the Prepare method.
Private Sub SqlCommandPrepareEx(ByVal connectionString As String)
Using connection As New SqlConnection(connectionString)
connection.Open()
Dim command As SqlCommand = New SqlCommand("", connection)
' Create and prepare an SQL statement.
command.CommandText = _
"INSERT INTO Region (RegionID, RegionDescription) " & _
"VALUES (@id, @desc)"
Dim idParam As SqlParameter = _
New SqlParameter("@id", SqlDbType.Int, 0)
Dim descParam As SqlParameter = _
New SqlParameter("@desc", SqlDbType.Text, 100)
idParam.Value = 20
descParam.Value = "First Region"
command.Parameters.Add(idParam)
command.Parameters.Add(descParam)
' Call Prepare after setting the Commandtext and Parameters.
command.Prepare()
command.ExecuteNonQuery()
' Change parameter values and call ExecuteNonQuery.
command.Parameters(0).Value = 21
command.Parameters(1).Value = "Second Region"
command.ExecuteNonQuery()
End Using
End Sub
private static void SqlCommandPrepareEx(string connectionString)
{
using (SqlConnection connection = new SqlConnection(connectionString))
{
connection.Open();
SqlCommand command = new SqlCommand(null, connection);
// Create and prepare an SQL statement.
command.CommandText =
"INSERT INTO Region (RegionID, RegionDescription) " +
"VALUES (@id, @desc)";
SqlParameter idParam = new SqlParameter("@id", SqlDbType.Int, 0);
SqlParameter descParam =
new SqlParameter("@desc", SqlDbType.Text, 100);
idParam.Value = 20;
descParam.Value = "First Region";
command.Parameters.Add(idParam);
command.Parameters.Add(descParam);
// Call Prepare after setting the Commandtext and Parameters.
command.Prepare();
command.ExecuteNonQuery();
// Change parameter values and call ExecuteNonQuery.
command.Parameters[0].Value = 21;
command.Parameters[1].Value = "Second Region";
command.ExecuteNonQuery();
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.
.NET Framework
Supported in: 2.0, 1.1, 1.0
.NET Compact Framework
Supported in: 2.0, 1.0