怎幺用sql语句实现用一个表某些字段更新另一个表同名字段?

[frogshero]

table A
aIndex b c
123 sd fgsd
25 asd dfg
3 asd sdfgg


table B
bIndex b c
123 sd fgsd
2345 ad dfg
311 asd sdfg

用b表中b.tIndex=a.Index的b,c字段更新a表的b,c字段

[97866]

Update a Set a.b=b.b,a.c=b.c from b where b.tIndex=a.Index

[yujohny]

update A
SET b= B.b,c=B.c
FROM B WHERE A.aIndex = B.bIndex

[txlicenhe]

Update a Set a.b=b.b,a.c=b.c
from a join b on b.Index=a.Index