How to Retrieve Return Values from Stored Procedures in C#?

Retrieving Return Values from Stored Procedures in C#

This article explores how to retrieve return values from stored procedures in C#.

Let's consider the following stored procedure named "[dbo].[Validate]":

ALTER PROCEDURE [dbo].[Validate]
@a varchar(50),
@b varchar(50) output

AS

SET @Password = 
(SELECT Password
FROM dbo.tblUser
WHERE Login = @a)

RETURN @b

To execute this stored procedure and retrieve the return value, you can use the following code:

using System;
using System.Data;
using System.Data.SqlClient;

namespace StoredProcedureReturnValue
{
    class Program
    {
        static void Main(string[] args)
        {
            // Assuming you have a connection string defined in your app config
            string connectionString = System.Configuration.ConfigurationManager.ConnectionStrings["MyLocalSQLServer"].ConnectionString;

            // Create a connection and command object
            using (SqlConnection SqlConn = new SqlConnection(connectionString))
            using (SqlCommand sqlcomm = new SqlCommand("Validate", SqlConn))
            {
                // Specify the stored procedure
                sqlcomm.CommandType = CommandType.StoredProcedure;

                // Add input parameters
                SqlParameter inputParam = new SqlParameter("@a", SqlDbType.VarChar, 50);
                inputParam.Value = "myUsername";
                sqlcomm.Parameters.Add(inputParam);

                // Add an output parameter to receive the return value
                SqlParameter outputParam = new SqlParameter("@b", SqlDbType.VarChar, 50);
                outputParam.Direction = ParameterDirection.ReturnValue;
                sqlcomm.Parameters.Add(outputParam);

                // Open the connection and execute the stored procedure
                SqlConn.Open();
                sqlcomm.ExecuteNonQuery();

                // Retrieve the output value
                string returnValue = (string)outputParam.Value;

                // Do something with the return value
                Console.WriteLine($"Return value: {returnValue}");
            }
        }
    }
}

Key points to note:

• Remember to call ExecuteNonQuery() on the SqlCommand object to execute the stored procedure.
• The direction of the output parameter must be set to ReturnValue to receive the return value.
• Finally, retrieve the return value from the Value property of the output parameter.

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