It's generally better to select the fields by name with your SQL query. If there got to be some problem with your data table, say a field got renamed somehow, your mysql_error statement would throw another helpful message.
I would suggest selecting ALL the fields from the given tables by name, unless performance is a paramount concern. That makes it easy to access that data in your app later with minimal changes. Then put your SQL statments in an included file so you can access that data from any page you need it without writing more code.