A表字段更新為B表的欄位值
T1表 結構
id name school
1 ming1 清華大學
2 ming2 北京大學
3 ming3 復旦大學
T2表 結構
id student school
11 ming1 牛津大學
12 ming3 劍橋大學
T1表的name 和 T2表的 student 值是 1對1 的對應。
需求:這兩個欄位的值相同時,根據B表的school更新A表的school。
語句:
update t1 set school = (select school from t2 where name=student) where exists (select * from t2 as b where name = b.student);
結果:
T1表 結構
id name school
1 ming1 牛津大學
2 ming2 北京大學
3 ming3 劍橋大學
注意:
條件裡不要再加本身要更新的表,
PS:
關聯查詢語句:
select aii.update_time,pn.public_time,pn.* from t_apply_item_instance aii, t_public_notice pn where pn.apply_item_instance_uuid = aii.uuid and
aii.apply_item_uuid in ('0101','0102','0103','0104','0105','0106','0201','0202','0203','0204','0205','0206') and aii.apply_status = 21
and pn.public_type = 1
更新語句:
update t_public_notice set public_time =
(select aii.update_time from t_apply_item_instance aii where apply_item_instance_uuid = aii.uuid and
aii.apply_item_uuid in ('0101','0102','0103','0104','0105','0106','0201','0202','0203','0204','0205','0206') and aii.apply_status = 21
and public_type = 1 )
where exists
(select t1.* from t_apply_item_instance as t1 where apply_item_instance_uuid = t1.uuid and
t1.apply_item_uuid in ('0101','0102','0103','0104','0105','0106','0201','0202','0203','0204','0205','0206') and t1.apply_status = 21
and public_type = 1)
update的表在後面的條件裡面是沒有了的