stored procedure returing a string for a C# app

Question

Hello all;

I have the following stored procedure below

create procedure dbo.test_sp (@p_para varchar(10) out)
as
begin
set @p_para = select 'this is a test'
return @p_para

c# code below

using (Sqlconnection conn = new SqlConnection(getconnectionstring()))
using (Sqlcommand cmd = conn.CreateCommand())
{

cmd.CommandText = "dbo.test_sp";
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add(@p_para, SqlDBType.String);

SqlParameter retval = new SqlParameter(@Returnval, System.Data.SqlDbType.String);
retval.Direction = System.Data.ParameterDirection.ReturnValue;
cmd.Paramters.Add(retval);
conn.Open();

cmd.ExecuteNonQuery();
string str_retval = retval.value.ToString();

}

However, I noticed, it doesn't return anything in my str_retval when I run my application and I don't know why. Thanks in advanced.

Answer 1

Try this C# code:

using (Sqlconnection conn = new SqlConnection(getconnectionstring()))  
using (Sqlcommand cmd = conn.CreateCommand())  
{  
   cmd.CommandText = "dbo.test_sp";  
   cmd.CommandType = CommandType.StoredProcedure;  
  
   SqlParameter para = cmd.Parameters.Add("@p_para", SqlDbType.String, 10);  
   para.Direction = ParameterDirection.Output;  
  
   conn.Open();  
   cmd.ExecuteScalar();  
  
   string str_retval = (String)para.Value;  
  
   // . . .  
}  

  

Answer 2

Try something like this:

create procedure dbo.test_sp (@p_para varchar(10) out)
as
begin
    set @p_para = 'this is a test'
end

. . .
retval.Direction = System.Data.ParameterDirection.Output;
. . .

Answer 3

Don't return parameter using return @Paramjeet Dahiya statement. Instead define your parameter as Output parameter, e.g.
in C# code use

SqlParameter outVal = new SqlParameter('@p_para', System.Data.SqlDbType.VarChar, 30 );  
  
outVal.Direction = ParameterDirection. Output;  
cmd.ExecuteNonQuery();  

string outValue = (string) outVal.Value;

Answer 4

Hi，@oly

Welcome to Microsoft T-SQL Q&A Forum!

You can add a line of statement in c#, use ExecuteScalar, see here for related links.

string p_para_ = SqlComm.ExecuteScalar();  

As a reminder, it's best to use catch to catch errors in execution, which can be very useful for your debugging.
and you need to distinguish between calling return values and returning strings, as Erland explained above.

Best regards,
Bert Zhou

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Answer 5

Hi All;

Unfortunately, I am getting the error messsage in C# stating the procedure or function test_sp expects parameter @p_para which was not supplied, does anyone know what that means,