SqlServer_update set from的用法整理

update set from 常用格式：

---不使用別名
UPDATE A  SET A1 = B1, A2 = B2, A3 = B3  
FROM A 
LEFT JOIN B ON A.ID = B.ID
--使用別名
UPDATE v1  SET A1 = B1, A2 = B2, A3 = B3  
FROM A as v1
LEFT JOIN B ON v1.ID = B.ID

一、批量更新操作，數據來自其他表的列或本表的其他列

注：

1.SqlServer update語句後面的table名稱，是不可以啓用別名的。

2.對應不同表的字段更新可以如下：

update Member_Info set MemberLevelName=(
select LevelName from Sys_Level 
where MemberLevelId=LevelId);
go

二、update set from 批量更新實例

1.不同表的修改

update Member_Info set MemberLevelName=L.LevelName
from Member_Info 
inner join Sys_Level L
on MemberLevelId=L.LevelId

2.表的自連接更新

update v1
set RecommendName=v1.NickName
from Member_Info as v1  
inner join Member_Info as v2 on v1.MemberId=v2.RecommendId

3.關聯表先彙總，然後更新字段

update t1
set InterestFreeze-=Amount,InterestThaw+=Amount
from Member_Info t1
inner join (
select MemberID,sum(Amount) as Amount from Member_Interest
where Type=1 and DaySum=10
group by MemberID
)  t2
on t1.MemberId=t2.MemberID