Stored procedure for search

Hi there,

First thing is first. Use SQL parameters in your query.

const string connectionStringName = "MyConnectionString";
            var searchText = "something";

            // Add your connection string to the config file. Then you can extract it like this
            using (var connection = new SqlConnection(ConfigurationManager.ConnectionStrings[connectionStringName].ToString()))
            {
                using (var command = connection.CreateCommand())
                {
                    // Use a stored procedure, if you can. That's better for performance
                    command.CommandType = CommandType.Text;
                    command.CommandText = "SELECT U.UserName as 'ID', U.FirstName + ' ' + U.LastName as 'Name' from [Users] U WHERE U.UserName LIKE @SearchText OR U.FirstName LIKE @SearchText OR U.LastName LIKE @SearchText";

                    var searchParameter = new SqlParameter("SearchText", searchText);
                    command.Parameters.Add(searchParameter);

                    connection.Open();
                    var reader = command.ExecuteReader();
                }
            }

Use Google or numerous articles on CodeProject to learn anything you don't understand in the above code block.

Now regarding your question. I've created a temp table and run your query like the way you have asked. It does NOT return any duplicates. Perhaps, you might have a different idea of what is a 'duplicate' or you might be trying to achieve something else. Please, explain what this SQL should return data-wise. Are you expecting just one row satisfying the search conditions?