This week's book giveaway is in the Performance forum. We're giving away four copies of The Java Performance Companion and have Charlie Hunt, Monica Beckwith, Poonam Parhar, & Bengt Rutisson on-line! See this thread for details.
why the sql String "select u.user_name,u.user_id from db_users u ,db_orders o where u.user_id=o.ore" can search what i want,but the String "select u.user_name,u.user_id from db_users u ,db_orders o,db_vip_users v where u.user_id=o.ore" show me "no rows"?
posted 13 years ago
Because your select result part of your sql contains no columns of the table v and your where part of the sql also have no connect string of the table v and u/o!