强类型数据集无法从存储过程中获取返回值

Question

I have a strongly-typed dataset that is using DBDirectMethods to insert data into a database using calls to stored procedures. The stored procedures return the primary key of the newly-created record. Here's a sample stored procedure:

CREATE PROCEDURE dbo.CreateUser
(
    @UserName   VARCHAR(50)
    @Password   VARCHAR(50)
)
AS

SET NOCOUNT OFF

DECLARE @UserID INT

BEGIN TRANSACTION

INSERT INTO dbo.Users (UserName, Password) VALUES (@UserName, @Password)

SET @UserID = SCOPE_IDENTITY()

INSERT INTO dbo.Users_History (UserID, Status, TimeStamp) VALUES (@UserID, 'C', GETUTCDATE())

COMMIT TRANSACTION

RETURN @UserID

GO

If I execute the stored procedure from SSMS, then the user account is created, the history table updated, and the primary key returned. If I run my application using the strongly-typed dataset and have SQL Profiler ticking away, I can see the same code being executed; however, the dataset returns -1 as the primary key and breaks the app.

Inside the VS-generated code for the table adapter, the relevant lines are:

this._adapter.InsertCommand.CommandText = "dbo.CreateUser";
this._adapter.InsertCommand.CommandType = global::System.Data.CommandType.StoredProcedure;
this._adapter.InsertCommand.Parameters.Add(new global::System.Data.SqlClient.SqlParameter("@RETURN_VALUE", global::System.Data.SqlDbType.Int, 4, global::System.Data.ParameterDirection.ReturnValue, 10, 0, null, global::System.Data.DataRowVersion.Current, false, null, "", "", ""));
this._adapter.InsertCommand.Parameters.Add(new global::System.Data.SqlClient.SqlParameter("@UserName", global::System.Data.SqlDbType.VarChar, 50, global::System.Data.ParameterDirection.Input, 0, 0, "UserName", global::System.Data.DataRowVersion.Current, false, null, "", "", ""));
this._adapter.InsertCommand.Parameters.Add(new global::System.Data.SqlClient.SqlParameter("@Password", global::System.Data.SqlDbType.VarChar, 50, global::System.Data.ParameterDirection.Input, 0, 0, "Password", global::System.Data.DataRowVersion.Current, false, null, "", "", ""));

and

try {
    int returnValue = this.Adapter.InsertCommand.ExecuteNonQuery();
    return returnValue;
}
finally {
    if ((previousConnectionState == global::System.Data.ConnectionState.Closed)) {
        this.Adapter.InsertCommand.Connection.Close();
    }
}

which is all just the standard boiler-plate code that VS usually generates - nothing has been edited by hand. It just doesn't pick up the return value.

I am running Windows 7 with SQL 2008 R2 SP1 Express.

Answer 1

From memory, the issue here is that the value ExecuteNonQuery () returns is the number of rows affected by the query.

Instead, your return value should be accessible via:

InsertCommand.Parameters["@RETURN_VALUE"].Value;

or

InsertCommand.Parameters[0].Value;

In addition, you can try changing your return parameter name to @UserID rather than @RETURN_VALUE but it should still work as you have it.

Answer 2

It seems that rather than returning only the PK, I need to return the entire new record. By changing my stored procedure to the following:

CREATE PROCEDURE dbo.CreateUser
(
    @UserName   VARCHAR(50)
    @Password   VARCHAR(50)
)
AS

SET NOCOUNT OFF

DECLARE @UserID INT

BEGIN TRANSACTION

INSERT INTO dbo.Users (UserName, Password) VALUES (@UserName, @Password)

SET @UserID = SCOPE_IDENTITY()

INSERT INTO dbo.Users_History (UserID, Status, TimeStamp) VALUES (@UserID, 'C', GETUTCDATE())

COMMIT TRANSACTION

SELECT UserID, UserName, Password FROM dbo.Users WHERE UserID = @UserID

GO

then ADO.NET automatically loads the returned result into the dataset, and I can get UserID from there.

Answer 3

您需要将查询类型从ExecuteNonQuery更改为ExecuteScalar，请参见http://blogs.msdn.com/b/smartclientdata/archive/2005/10/31/returnidentityvaluequery.aspx