单表
update tableName set xxx='' where xx=''
//多表
UPDATE T1 SET xxx= t2.xxx
FROM tableName1 T1 WITH(NOLOCK)
INNER JOIN tableName2 T2 ON T1.xx= T2.xx
单表
update tableName set xxx='' where xx=''
//多表
UPDATE T1 SET xxx= t2.xxx
FROM tableName1 T1 WITH(NOLOCK)
INNER JOIN tableName2 T2 ON T1.xx= T2.xx