I\'m trying to return a single row from a database:
using (connection = new SqlConnection(ConfigurationManager.AppSettings[\"connection\"])) { using (command
The problem is the return type. The method you are in is expecting you to return a string, but reader["col_1"] is an object. I suggest returning reader["col_1"].ToString() or Convert.ToString(reader["col_1"]).
reader["col_1"]
reader["col_1"].ToString()
Convert.ToString(reader["col_1"])