表A有字段A1,A2,表B中有A1,A2,但表B中的A2的空的。要根据表A的A1与表B的A1(两个A1可以一一对应),跟新B中的A2 ,Sql语句应怎么写?
------解决方案--------------------
update b
set b.a2=a.a2
from a inner join b on a.a1=b.a1
------解决方案--------------------
update b
set b.a2=(select a2 from a where a.a1=b.a1) and exists(select 1 from a2 from a where a.a1=b.a1)
DB2BT的写法