求一条更新SQL语句

表A col1 col2 col3
表B col1 col2 col3
用表A left join 表B
where A.col1=B.col1
A.col2=B.col2
写一条SQL更新:将表B.col3全部赋值给A.col3

update A set col3 = (select col3 from B);

你是要把表B.col3全部赋值给A.col3 还是将A.col3赋值给B.col3啊？

表B.col3全部赋值给A.col3 ：

update A set A.col3 =B.col3 from A,B where A.col1=B.col1 and A.col2=B.col2

将A.col3赋值给B.col3

update B set B.col3 =A.col3 from A,B where A.col1=B.col1 and A.col2=B.col2

行不？

update tpA set tpA.col3 = tpB.col3 from A as tpA,B as tpB where tpA.col1=tpB.col1 and tpA.col2=tpB.col2

update A set col3 = (select col3 fromleft join 表B where A.col1=B.col1 A.col2=B.col2 );

insert into A(col3) select col3 from B