.net - Procedure expects parameter which was not supplied

Question

I'm getting the error when accessing a Stored Procedure in SQL Server

Server Error in '/' Application.
Procedure or function 'ColumnSeek' expects parameter '@template', which was not supplied. 

This is happening when I call a Stored Procedure with a parameter through .net's data connection to sql (System.data.SqlClient), even though I am supplying the parameter. Here is my code.

SqlConnection sqlConn = new SqlConnection(connPath);
sqlConn.Open();

//METADATA RETRIEVAL
string sqlCommString = "QCApp.dbo.ColumnSeek";
SqlCommand metaDataComm = new SqlCommand(sqlCommString, sqlConn);
metaDataComm.CommandType = CommandType.StoredProcedure;
SqlParameter sp = metaDataComm.Parameters.Add("@template",SqlDbType.VarChar,50);
sp.Value = Template;

SqlDataReader metadr = metaDataComm.ExecuteReader();

And my Stored Procedure is:

   USE [QCApp]
   GO
   SET ANSI_NULLS ON
   GO
   SET QUOTED_IDENTIFIER ON
   GO

   ALTER PROCEDURE [dbo].[ColumnSeek] 
       @template varchar(50)
   AS
   EXEC('SELECT Column_Name, Data_Type 
   FROM [QCApp].[INFORMATION_SCHEMA].[COLUMNS] 
   WHERE TABLE_NAME = ' + @template);

I'm trying to figure out what I'm doing wrong here.

Edit: As it turns out, Template was null because I was getting its value from a parameter passed through the URL and I screwed up the url param passing (I was using @ for and instead of &)

Answer 1

In addition to the other answers here, if you've forgotten to put:

cmd.CommandType = CommandType.StoredProcedure;

Then you will also get this error.