update a set value = (select value from b where b.key = a.key) where exists (select 1 from b where b.key = a.key)
--merge into merge into a using b on(a.key=b.key) when matched then update set a.value=b.valueupdate a set a.value=(select value from b where a.key=key) case when...then...else..end中可以嵌套几个else? 一个
update a set a.value=(select value from b where a.key=key) 晕!!!
set value = (select value from b
where b.key = a.key)
where exists (select 1 from b
where b.key = a.key)
merge into a using b on(a.key=b.key)
when matched then update set a.value=b.valueupdate a set a.value=(select value from b where a.key=key)
case when...then...else..end中可以嵌套几个else?
一个
晕!!!