存储过程什么也不返回

Question

This might be a simple fail on my part, but I just can't figure out where or how. I've been coding a windows service that is doing a bunch of things. One of which is inserting and getting data from a MS Sql 2005 database through stored procedures.

The following code is part of a windows service and now also a windows form, where both produce the same empty result.

    try
        {
            SqlCommand cmd = new SqlCommand("U_RfId_ProductNumberGet", connectionRFID);
            cmd.CommandType = System.Data.CommandType.StoredProcedure;
            //SqlParameter paramProd = new SqlParameter();
            SqlParameter paramOut = new SqlParameter();
            paramOut.ParameterName = "@ProductInformation";
            paramOut.Direction = System.Data.ParameterDirection.Output;
            paramOut.SqlDbType = System.Data.SqlDbType.VarChar;
            paramOut.Size = 50;
            cmd.Parameters.Add(paramOut);
            cmd.Parameters.AddWithValue("@ProductNumber", content); //content = "1" for testing
            connectionRFID.Open();

            textBox1.Text = (String)paramOut.Value;

            //cmd.Parameters["@ProductInformation"].Value.ToString();
            connectionRFID.Close();
        }
        catch (Exception ex)
        { textBox1.Text = ex.Message;
        connectionRFID.Close();
        }

And then there's the SP the code is calling. I've tried changing it to only return a resultset instead of a scalar output parameter and then the call to the SP works, but I'd prefer to use the scalar values.

CREATE PROCEDURE U_RfId_ProductNumberGet
@ProductInformation     varchar(50) OUTPUT,
@ProductNumber          varchar(8)

AS
BEGIN TRAN
SET NOCOUNT ON;
BEGIN
SELECT @ProductInformation
                = CAST(vareNummer AS varchar(10)) 
                + '-' + CAST(vareTekst AS varchar(30))
FROM VareNummerVareTekst
WHERE ProductNumber = @ProductNumber
END
COMMIT TRAN

As a side note: If I execute the SP through SQL Management Studio I get a valid result.

Anyone notice what I've forgotten?

Answer 1

You forgot to execute the command.

cmd.Execute(); // to get a resultset

or

cmd.ExecuteNonQuery(); // to get output parameters but no resultset 

should do it depending on whether or not you want a resultset.

Answer 2

you have to use ExecuteNonQuery on command object. SqlCommand Executenonquery

    connectionRFID.Open();
    cmd.ExecuteNonQuery(); // this missing from your code 
   textBox1.Text = (String)paramOut.Value;