How to use subquery in delete/update query in mysql

问题

I am using a mysql 5.0.77 database using the query:

Delete from IPADDRESS
where visitdate Not in (SELECT max(visitdate) FROM IPADDRESS WHERE USERNAME='MGSH0002') 
and USERNAME='MGSH0002' 

I am getting this error when executed:

You can't specify target table IPADDRESS for update in from clause

回答1:

Certainly not the best solution but for your problem this will do the trick:

delete i1 from
  IPADDRESS i1,
  IPADDRESS i2
where
  i1.username = i2.username
  and i1.username = 'MGSH0002'
  and i1.visitdate < i2.visitdate

An alternative and much more smarter solution is the following statement:

delete i1 from
  IPADDRESS i1,
  (select max(visitdate) visitdate from IPADDRESS where username = 'MGSH0002') temp
where
  i1.username = 'MGSH0002'
  and i1.visitdate < temp.visitdate

回答2:

You can't, unfortunately MySql doesn't allow this.

Currently, you cannot update a table and select from the same table in a subquery.

From:

http://dev.mysql.com/doc/refman/5.0/en/update.html

来源：https://stackoverflow.com/questions/9907484/how-to-use-subquery-in-delete-update-query-in-mysql