sql 批量更新某個字段的值

UPDATE Tabel1 t1 set t1.col1= 
( SELECT  col2  from Tabel2 t2 WHERE  t1.col1=t2.col2) 
where exists
( SELECT  col2  from Tabel2 t2 WHERE  t1.col1=t2.col2) 

更新Table1 和Table1 匹配的值 中 表Table1 中col1 列的值