有如下两表:a表:
aid title
-------------
1 111
2 222b表:
bid aid image time
-----------------------------------------
1 2 1.gif 2007-08-08 00:00:00
2 2 2.gif 2007-08-09 00:00:00
3 2 3.gif 2007-08-08 00:00:00
如何得到如下的结果呢?
(即a表与b表关联,取出b表中最新的一条数据,且a表中的数据不可重复出现)aid title image time
-----------------------------------------
1 111 NULL NULL
2 222 2.gif 2007-08-09 00:00:00
用下面的语句是错误的 ;-(
SELECT a.aid, a.title, b.image, b.time FROM a LEFT JOIN b ON b.aid = a.aid ORDER BY b.time DESC
aid title
-------------
1 111
2 222b表:
bid aid image time
-----------------------------------------
1 2 1.gif 2007-08-08 00:00:00
2 2 2.gif 2007-08-09 00:00:00
3 2 3.gif 2007-08-08 00:00:00
如何得到如下的结果呢?
(即a表与b表关联,取出b表中最新的一条数据,且a表中的数据不可重复出现)aid title image time
-----------------------------------------
1 111 NULL NULL
2 222 2.gif 2007-08-09 00:00:00
用下面的语句是错误的 ;-(
SELECT a.aid, a.title, b.image, b.time FROM a LEFT JOIN b ON b.aid = a.aid ORDER BY b.time DESC
ORDER BY b.time asc;
aid title image time
1 111 (NULL) (NULL)
2 222 2.gif 2007-08-09