查询以获取mysql中同一列中的多个字段

Question

I am using mysql db.

     id | comment       
--------+--------------- 
   1121 |    Accounting
   1121 |    Shipping  
   1121 |    Receiving
   1121 |    Testing
   1122 |    Accounting
   1122 |    Receiving

I want to write such a query so that o/p will be like this-:

     id | comment       
--------+--------------- 
   1121 |    Accounting
   1121 |    Shipping  
   1121 |    Receiving
   1121 |    Testing

So I want Accounting, Shiping, Receiving and testing comments.

Can anybody plz guide me??

Answer 1

• If you only want the id of records that contain all four comments, you can group by id and filter such groups for those that contain the requisite number of records:

   SELECT id FROM my_table WHERE comment IN ('Accounting', 'Shipping', 'Receiving', 'Testing') GROUP BY id HAVING COUNT(*) = 4 

  See it on sqlfiddle .

• If you want the complete records for such (id, comment) pairs, you can join the result with your original table:

   SELECT * FROM my_table NATURAL JOIN ( SELECT id FROM my_table WHERE comment IN ('Accounting', 'Shipping', 'Receiving', 'Testing') GROUP BY id HAVING COUNT(*) = 4 ) t WHERE comment IN ('Accounting', 'Shipping', 'Receiving', 'Testing') 

  See it on sqlfiddle .

Note that if your data model does not guarantee uniqueness of (id, comment) pairs, you will need to replace COUNT(*) with (the less performant) COUNT(DISTINCT comment) in the above queries.

Answer 2

Do you want to select all IDs, that have all 4 comments? In your example 1121 has 4 different comments (it's like a "state", right?), and 1122 has only 2 states (comments).

select T1.id from mytable T1, mytable T2, mytable T3, mytable T3 where T2.id=T1.id and T3.id=T1.id and T4.id=T1.id and T1.comment='Accounting' and T2.comment='Shipping' and T3.comment='Receiving' and T4.id='Shipping'