无法从存储过程中获取值

Question

I am trying to get the value from a stored procedure, below is my code

SqlConnection connection = new SqlConnection("");
connection.Open();
DataTable timeZoneDt = new DataTable();
var sqlCommand = new SqlCommand("GetTimeZoneGMT", connection);
sqlCommand.CommandType = CommandType.StoredProcedure;
sqlCommand.Parameters.Add("@TimeZone", SqlDbType.NVarChar).Value = "Asia/Kuala_Lumpur";
//timeZoneDt.Load(sqlCommand.ExecuteReader());
//new SqlDataAdapter(sqlCommand).Fill(timeZoneDt);

var reader2 = sqlCommand.ExecuteReader();


while (reader2.Read())
{
    var ID = int.Parse(reader2[0].ToString());
}
connection.Close();

the following is my stored procedure,

/****** Object:  StoredProcedure [dbo].[GetTimeZoneGMT]    Script Date: 23/4/2018 4:05:46 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO


ALTER PROCEDURE [dbo].[GetTimeZoneGMT]
    @TimeZone NVARCHAR(128)
AS
BEGIN
 DECLARE @timeZoneNumber as INT = -20;
 IF @TimeZone ='Pacific/Midway'
 SET @timeZoneNumber = -11
 ELSE IF @TimeZone ='Pacific/Niue'
 SET @timeZoneNumber = -11
 ELSE IF @TimeZone ='Pacific/Pago_Pago'
 SET @timeZoneNumber = -11

 RETURN @timeZoneNumber;
END

I cannot write it all to you all because the timezone have 400 rows, however it is similiar like this.

However, when i get my c# code, it is empty value, why? whats wrong with the code

Answer 1

You need to declare a parameter for the ReturnValue even if you don't have it in your Stored Procedure declaration. You can name the parameter whatever you like but you should mark it as ParameterDirection.ReturnValue .

SqlParameter r = cmd.Parameters.Add("@timeZoneNumber", SqlDbType.Int);
r.Direction = ParameterDirection.ReturnValue;
cmd.ExecuteNonQuery();

int result = Convert.ToInt32(r.Value);

Notice that you don't need to call ExecuteReader but just ExecuteNonQuery.