嵌套查询语句的MySQL查询

Question

I have a table like this:

id   method  callid
-------------------------
1    INVITE  pW.wKkwjxt
2    BYE     pW.wKkwjxt
3    INVITE  YcIEWypRd
4    BYE     YcIEWypRd
5    INVITE  .--.jr1oji1ddt
6    BYE     .--.jr1oji1ddt
7    INVITE  rM7D3IhQR
8    INVITE  kUc0YNjQy
9    INVITE  S07wSM3G
10   BYE     rM7D3IhQR

In this table method column having 2 methods INVITE and BYE with same callid. I need the query like the callid having INVITE and not having BYE with the same callid

Output like this:

id  method  callid
---------------------
8   INVITE  kUc0YNjQy
9   INVITE  S07wSM3G 

I tried with below query but not getting correct output.

SELECT `ac1`.`method`,`ac2`.`method`,`ac1`.`callid`,`ac2`.`callid`,`ac1`.`id`,`ac2`.`id` 
FROM `acc` `ac1`
join `acc` `ac2` ON `ac1`.`callid` = `ac2`.`callid` and `ac2`.`method` != 'BYE'

Any one can help me please.

Answer 1

You can do a left join on the callid, when it has no matching callid then it will be null so you can do a2.id IS NULL to filter those out.

SELECT `ac1`.`method`,`ac2`.`method`,`ac1`.`callid`,`ac2`.`callid`,`ac1`.`id`,`ac2`.`id` 
FROM acc a1
LEFT JOIN acc a2 ON a2.callid=a1.callid AND a2.method='BYE'
WHERE a1.method='INVITE' 
AND a2.id IS NULL