sql语句问题:更新表的问题

[maggie_ma]

例如有两个表:table1, table2


table2表的结构是id,tid,address

table1表的结构是tid,num


我要做的是select num=count(*),tid from table2 group by tid

将得到的相对应的tid,更新table1表的相应的num值
update table1 set num = .....where tid = ....

例如记录: table1 表
tid num
1 null
2 null

table2表
id, tid, address
1 1 192.121.0.1
2 1 192.121.0.2
3 2 192.155.0.1


结果: talbe1表
tid num
1 2
2 1


请教sql语句怎么写

[javaCoffee33]

update table1 set num = (select count(*) from table2 where table1.tid = table2.tid )

先试试把

[godhuang]

select tid,count(*) as num into T# from table1 group by tid
insert into table2 select * from T#
drop table T#