Why would changing the parameter name in a parameterized query cause an SqlException to be thrown?

Question

My Original query used @WF_ID as the parameter name and would execute without any problems. I am lazy though and WF_ was to much typing so I renamed the parameter to @ID but now when executed an SQLException is thrown. The exact message is "Invalid column name '_Page'"

Here are the two versions of the query and corresponding code. As you can see the only thing that has changed is the parameter name.

SQL_Connection.Open();
SQL_Command.Connection = SQL_Connection;
SqlParameter param = new SqlParameter("@WF_ID", SqlDbType.Int);
param.Value = WF_ID;
SQL_Command.Parameters.Add(param);
SQL_Command.CommandText = "SELECT COUNT(*) AS MyCount from members WHERE ID = @WF_ID";
int numRows = Convert.ToInt32(SQL_Command.ExecuteScalar().ToString());
SQL_Command.Parameters.Clear();

Version 2.0 the broken version

 SQL_Connection.Open();
 SQL_Command.Connection = SQL_Connection;
 SqlParameter param = new SqlParameter("@ID", SqlDbType.Int);
 param.Value = WF_ID;
 SQL_Command.Parameters.Add(param);
 SQL_Command.CommandText = "SELECT COUNT(*) AS MyCount from members WHERE ID = @ID";
 int numRows = Convert.ToInt32(SQL_Command.ExecuteScalar().ToString());
 SQL_Command.Parameters.Clear();

My Initial thought was a parameter name cannot be the same as one of the column names...but I can't find anything that explicitly says that.

Looking at this StackOverflow topic it would seem that you couldn't pass a column name via parameters. Can I pass column name as input parameter in SQL stored Procedure

Answer 1

"SELECT COUNT(*) AS MyCount from members WHERE ID = " + @WF_ID;

This is not a parameterized query at all. You just concatenated the value to your SQL string.

"SELECT COUNT(*) AS MyCount from members WHERE ID = @WF_ID";

This would make it use your parameter.