How to Retrieve Stored Procedure Return Values in C#?

Retrieve stored procedure return value in C#

When calling a stored procedure that returns a value in C#, it is crucial to correctly handle the return value in the code. This article describes this problem and provides a solution for successfully retrieving return values ​​from stored procedures.

Problem Statement

A C# application needs to call a stored procedure that returns the next value in a sequence. Despite following the solutions online, I still cannot retrieve the return value. The provided code snippet includes creating a SqlCommand object, specifying the stored procedure as the command text, and using a SqlConnection to execute the command. However, the return value of the stored procedure is not retrieved.

Store procedure code

ALTER procedure [dbo].[usp_GetNewSeqVal]
      @SeqName nvarchar(255)
as
begin
      declare @NewSeqVal int
      set NOCOUNT ON
      update AllSequences
      set @NewSeqVal = CurrVal = CurrVal+Incr
      where SeqName = @SeqName

      if @@rowcount = 0 begin
print 'Sequence does not exist'
            return
      end

      return @NewSeqVal
end

C# code to call stored procedure

SqlConnection conn = new SqlConnection(getConnectionString());
conn.Open();

SqlCommand cmd = new SqlCommand(parameterStatement.getQuery(), conn);
cmd.CommandType = CommandType.StoredProcedure;

SqlParameter param = new SqlParameter();

param = cmd.Parameters.Add("@SeqName", SqlDbType.NVarChar);
param.Direction = ParameterDirection.Input;
param.Value = "SeqName";

SqlDataReader reader = cmd.ExecuteReader();

Solution

To get the return value of the stored procedure, you need to add a parameter with the ReturnValue direction to the SqlCommand object. This instructs the command to declare a variable and assign the return value of the stored procedure to it. The following code demonstrates the solution:

using (SqlConnection conn = new SqlConnection(getConnectionString()))
using (SqlCommand cmd = conn.CreateCommand())
{
    cmd.CommandText = parameterStatement.getQuery();
    cmd.CommandType = CommandType.StoredProcedure;
    cmd.Parameters.AddWithValue("SeqName", "SeqNameValue");

    // @ReturnVal 可以是任何名称
    var returnParameter = cmd.Parameters.Add("@ReturnVal", SqlDbType.Int);
    returnParameter.Direction = ParameterDirection.ReturnValue;

    conn.Open();
    cmd.ExecuteNonQuery();
    var result = returnParameter.Value;
}

The above is the detailed content of How to Retrieve Stored Procedure Return Values in C#?. For more information, please follow other related articles on the PHP Chinese website!