多表关联的update语句
ORACLE?UPDATE?多表关联的update语句
??--?update?超过2个值
???update?customers?a???--?使用别名
???set????(city_name,customer_type)=(select?b.city_name,b.customer_type?
?????????????????????????????????????from???tmp_cust_city?b?
?????????????????????????????????????where??b.customer_id=a.customer_id)
???where??exists?(select?1?
??????????????????from???tmp_cust_city?b
??????????????????where??b.customer_id=a.customer_id
?????????????????)
?
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MSSql的多表关联的update语句?例如A表 存在一下字段:
AID A1 A2 A3 A4
B表中存在字段：
BID B1 B2 B3 B4
如果实现用B表的所有字段更新A表中相应的字段，在MS SQL Server里面可以写成：
update A
set A1=B.B1,A2=B.B2,A3=B.B3,A4=B.B4
from A,B
where A.AID=B.BID