ORACLE 中IN和EXISTS比较
摘要：
EXISTS的执行流程 select * from t1 where exists ( select null from t2 where y = x ) 可以理解为: for x in ( select * from t1 ) loop if ( exists ( select null from t2 where y = x.x ) ... 阅读全文
posted @ 2009-01-12 17:14 不过 阅读(66761) 评论(1) 推荐(2) 编辑
