CODEWITHSUNDEEP
sqlsql-server
mHelpMe
mHelpMe

Reputation: 6668

Nested SELECT query with COUNT condition

I have two tables. I have a simple inner join query where fields are selected from two tables, Deals and Deals_Country.

Both tables share a field called Id. This is a primary key in Deals & a foreign key in Deals_Country. So an id is always unique in Deals but not always unique in Deals_Country.

I want to add a further condition to my simple inner join query. I want to return only records where there is more than one id in MA_DEALS_COUNTRY. Please see an example below.

 select DEALS.id, DEALS.field_b, DEALS_COUNTRY.field_c DEALS_COUNTRY.field_d, 
 from DEALS
 inner join DEALS_COUNTRY
 on DEALS.id = DEALS_COUNTRY.id
 where 
 (
    select id
    from DEALS_COUNTRY
    group by id
    having count(id) > 1
 ) 
 order by id


DEALS
id
AA11
AB34
AN21
BN44

DEALS_COUNTRY
id      some_code
AA11    4506
AB34    5052
AB34    6161
AB34    0124
AN21    6322
AN21    9548
BN44    0012

Result

Deal.id    Deal_Country.some_code
AB34       5052
AB34       6161
AB34       0124
AN21       6322
AN21       9548

Upvotes: 0

Views: 725

Answers (2)

Paul Maxwell
Paul Maxwell

Reputation: 35573

an alternative approach is to use count() over()

SELECT
      id
    , field_b
    , field_c
    , field_d
FROM (
            SELECT
                  DEALS.id
                , DEALS.field_b
                , DEALS_COUNTRY.field_c
                , DEALS_COUNTRY.field_d
                , COUNT(*) OVER (PARTITION BY DEALS_COUNTRY.id) AS cnt
            FROM DEALS
                  INNER JOIN DEALS_COUNTRY
                              ON DEALS.id = DEALS_COUNTRY.id
      ) AS sq
WHERE cnt > 1

Upvotes: 1

Squirrel
Squirrel

Reputation: 24763

select DEALS.id, DEALS.field_b, DEALS_COUNTRY.field_c DEALS_COUNTRY.field_d, 
 from DEALS
 inner join DEALS_COUNTRY
 on DEALS.id = DEALS_COUNTRY.id
 where  exists
 (
    select x.id
    from DEALS_COUNTRY x
    where  x.id = DEALS.id
    group by x.id
    having count(x.id) > 1
 ) 
 order by deal_id

Upvotes: 1

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