ORACLE允许根据一个表UPDATE另外一个表的纪录吗？好像SQL可以

Question

update CUSTOMER_TRANSACTION a set CUSTOMER_ID= ( select CUSTOMER.CUSTOMER_ID
from CUSTOMER b where a.CUSTOMER_NAME=b.NAME)
where exists (select 1 from CUSTOMER c where a.CUSTOMER_NAME=c.NAME);

Answer 1

update CUSTOMER_TRANSACTION set CUSTOMER_ID=select CUSTOMER.CUSTOMER_ID from CUSTOMER where CUSTOMER_TRANSACTION.CUSTOMER_NAME=CUSTOMER.NAME

Answer 2

update CUSTOMER_TRANSACTION set CUSTOMER_ID=(select DISTINCT CUSTOMER_ID from CUSTOMER
where CUSTOMER.NAME=CUSTOMER_TRANSACTION.CUSTOMER_NAME)对每一个CUSTOMER.NAME，select出来的id必须只有一个值，否则会出错

Answer 3

to:Lastdrop(空杯) 
最后一句：
where exists (select 1 from CUSTOMER c where a.CUSTOMER_NAME=c.NAME);
能起作用吗？
当c表中找不到 a.CUSTOMER_NAME，那怎么update？

Answer 4

lastdrop的不会出任何错误，如果词表中找不到a.customer_name,就不更新了。或者你可以：
case when exists (select 1 from CUSTOMER c where a.CUSTOMER_NAME=c.NAME)
     then update CUSTOMER_TRANSACTION a set CUSTOMER_ID= ( select     CUSTOMER.CUSTOMER_ID from CUSTOMER b where a.CUSTOMER_NAME=b.NAME)
else
     处理语句
end

Answer 5

update CUSTOMER_TRANSACTION set CUSTOMER_ID=(select CUSTOMER.CUSTOMER_ID from CUSTOMER where CUSTOMER_TRANSACTION.CUSTOMER_NAME=CUSTOMER.NAME)
注意:CUSTOMER_TRANSACTION.CUSTOMER_NAME=CUSTOMER.NAME必需唯一