数据库更新表数据，从另一个表中取值

[goohugo]

SQL SERVER

UPDATE  A set A.C=B.C 
from  tableA  as A（别名）,tableB as  B （别名）
where A.列= B.列

MySQL

UPDATE tableA  as A
inner join tableB as  B  
on  A.列= B.列
set  A.C=B.C 

当A表与B表某个字段值相等时，更新A表某列值等于B表某列值

DB2

UPDATE A_TEST as atest
set atest.ORG_CODE=(select ctest.code from C_TEST ctest where atest.id = ctest.id)
where atest.id in  (select ctest.id FROM TEST ctest);