有两个表联接的mysql查询

Question

Folks

I have 2 tables countrycodes,cctonumbers as described below.

I have the query that i tried but not getting the desired output.

My Output

 country          destination                     country_code   destination_code

Afghanistan  Afghanistan Mobile Etisalat              93        78
Afghanistan  Afghanistan Mobile Etisalat              93        72
Afghanistan  Afghanistan Mobile Roshan                93        79
Afghanistan  Afghanistan                              93        93

Desired output

country          destination                     country_code   destination_code

Afghanistan  Afghanistan Mobile Etisalat             93           78

Afghanistan  Afghanistan Mobile Etisalat             93           72    

Afghanistan  Afghanistan Mobile Roshan               93           79

The tables used are as below

countrycodes table

id       parentid   countryname 
1031     0          afghanistan 
1035     1031       Afghanistan Mobile Etisalat
1036     1031       Afghanistan Mobile Roshan

cctonumbers table

id       countrycode_id     parentid         number 
15731    1031               0                93
15197    1035               15731            78
15198    1035               15731            72
15199    1036               15731            79

The query that im using is as below but not getting desired result.

select * 
   from 
      cctonumbers 
         LEFT JOIN countrycodes as CC 
            ON cctonumbers.countrycode_id = CC.id 
   WHERE 
      (     CC.parentid=0 
        AND number like '93%'
        and cctonumbers.id in 
                ( select cctonumbers.parentid 
                     from cctonumbers 
                        LEFT JOIN countrycodes as CC 
                           ON cctonumbers.countrycode_id = CC.id 
                        WHERE number like '7%'
                          AND CC.parentid!=0 )
                ) 
          or (     CC.parentid != 0 
               AND number like '7%' 
               AND CC.parentid in 
                       ( select CC.id 
                            from cctonumbers 
                               LEFT JOIN countrycodes as CC 
                                  ON cctonumbers.countrycode_id=CC.id 
                            WHERE CC.parentid=0 
                              AND number like '93%' )
             ) 
   ORDER BY 
      cctonumbers.number Asc

Answer 1

What you appear to be looking for is all destinations associated with a specific country code. Since you not actually showing any return results for your cctonumbers.id = 15731, I think you were spinning to get your results. Let's reverse the tree instead of walking down it.

Start with only those CCToNumbers records that have a parent ID as it appears you are only 1-level deep. Once you have those child-level entries, join back to CCToNumbers on its parent... then go to the country codes tables for both respectively.

SELECT
      CtoN.ID,
      PCountry.CountryName,
      DCountry.CountryName as Destination,
      CtoNParent.Number as Country_Code,
      CtoN.Number as Destination_Code
   from 
      cctonumbers CtoN
         JOIN cctonumbers as CtoNParent
             ON CtoN.parentid = CtoNParent.ID
            AND CtoNParent.number like '93%'
            JOIN countrycodes as PCountry
               ON CtoNParent.CountryCode_Id = PCountry.ID
         JOIN countrycodes as DCountry
            ON CtoN.CountryCode_Id = DCountry.ID
   where
      CtoN.number like '7%'