SQL语句的并集UNION,交集JOIN(内连接,外连接),交叉连接(CROSS
摘要:
SQL语句的并集UNION,交集JOIN(内连接,外连接),交叉连接(CROSS JOIN笛卡尔积),差集(NOT IN)1.a. 并集UNIONSELECT column1, column2 FROM table1UNIONSELECT column1, column2 FROM table2b. 交集JOINSELECT * FROM table1 AS a JOIN table2 b ON ... 阅读全文
posted @ 2010-06-04 11:08 梦想的起点 阅读(459) 评论(0) 推荐(0) 编辑