How to fetch the unmapped records in mysql

I'm using MySQL database and my table structure is as like:

+---------------+----------------+-------------------+
| leave_type_id | leave_type     | leave_type_org_id |
+---------------+----------------+-------------------+
|            23 | Casual Leave   |                33 | 
|            24 | Earn Leave     |                 0 | 
|            33 | Sick Leave     |                 0 | 
|            34 | CL   Leave     |                 0 | 
|            35 | PL   LEAVE     |                23 | 
|            42 | EL   LEAVE     |                 0 | 
+----------开发者_JAVA百科-----+----------------+-------------------+

and i want to fetch only the unmapped records from my table leave_type, mean which leave_type_id is not present inside the leave_type_org_id like (24, 34, 35, 42) plz send me the query as in reply asap. Thanks.

You could do join on same table like this

select t1.* 
from table t1
left join table t2
on t1.leave_type= t2.leave_type_org_id
where t2.leave_type_org_id is null

OR

With sub query

select * from table 
where leave_type_id not in 
(
    select leave_type_org_id from table  
)