Get result from Stored Procedure then pass to WPF TextBox - sql

Question

I have this stored procedure that executes fine:
ALTER PROCEDURE [dbo].[SP_GENERATETICKET]
#RESULT AS VARCHAR(255) OUTPUT
AS
BEGIN
DECLARE #D AS DATETIME = GETDATE()
DECLARE #LASTTICKET AS VARCHAR(50) ;
DECLARE #NUM AS VARCHAR(50);
SET #LASTTICKET=(SELECT TOP 1 TICKETNO FROM tblTicket WHERE
MONTH(ENTRYVEHICLE ) = MONTH(#D ) ORDER BY TICKETNO DESC);
IF (CONVERT(VARCHAR(10),YEAR(#D),110) <> CONVERT(VARCHAR(10),YEAR(GETDATE()),110))--IF YEAR IS DIFFERENT, RESET SERIES
BEGIN
SET #NUM = '1'
END
ELSE
BEGIN
IF ISNULL(#LASTTICKET,'1') = '1'--IF MONTH IS DIFFERENT, RESET SERIES
BEGIN
SET #NUM ='1'
END
ELSE
BEGIN
SET #NUM = CAST(CAST (RIGHT(#LASTTICKET,5) AS INT) + 1 AS VARCHAR)
END
END
SET #RESULT = RIGHT(CONVERT(VARCHAR(10),#D,101),2) + '-' + LEFT(CONVERT(VARCHAR(10),#D,101),2) + '-' + RIGHT('0000'+CAST(#NUM AS VARCHAR),5)
SELECT #RESULT
END
I have this Code but it returns null
SqlConnection con = new SqlConnection(gsql.connectionString);
SqlCommand command = new SqlCommand("SP_GENERATETICKET", con);
try
{
con.Open();
command.CommandType = CommandType.StoredProcedure;
SqlParameter result = command.Parameters.Add("#RESULT", SqlDbType.VarChar);
result.Direction = ParameterDirection.Output;
txtTicket.Text = (string)command.Parameters["#RESULT"].Value;
}
catch(Exception ex)
{
MessageBox.Show(ex.Message);
}
What should I do?

Answer 1

there problem is there , you forgot to execute command
command.ExecuteNonQuery()
without executing command you want get result back.
also you forgot to add size for you varchar paramter , so add thing line
result.Size = 8000;
udpated in below code
you code will be , you need to use using to dispose things for you
using(SqlConnection con = new SqlConnection(gsql.connectionString))
{
using(SqlCommand command = new SqlCommand("SP_GENERATETICKET", con))
{
try
{
con.Open();
command.CommandType = CommandType.StoredProcedure;
SqlParameter result = command.Parameters.Add("#RESULT", SqlDbType.VarChar);
result.Size = 8000;//add parameter size
result.Direction = ParameterDirection.Output;
command.ExecuteNonQuery();//this line need to be added
txtTicket.Text = (string)command.Parameters["#RESULT"].Value;
}
catch(Exception ex)
{
MessageBox.Show(ex.Message);
}
}
}

Answer 2

Parameters are a good practice but for output you cannot have SQL injection (that I know of).
con.Open();
command.CommandType = CommandType.StoredProcedure;
txtTicket.Text = (string)command.ExecuteScalar();
For size you can use this syntax:
SqlParameter result = command.Parameters.Add("#RESULT", SqlDbType.VarChar, 800);