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Editorial Team
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Asked: 2026-05-23T10:18:02+00:00

Intro I have a complex query I need to write (for an Oracle DB).

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Intro

I have a complex query I need to write (for an Oracle DB). I’ve tried to make an analogy to avoid using company data, so let me know if something seems weird.

Tables

CAT

  • CAT_ID (PK)

KITTEN

  • KITTEN_ID (PK)

CAT_KITTEN_PLAY

  • PLAY_ID (PK)
  • CAT_ID (FK to CAT table)
  • KITTEN_ID (FK to KITTEN table)
  • KITTEN_GENDER (String – M or F)
  • PLAY_TIME (Date)

KITTEN_INFO

  • KITTEN_ID (FK to KITTEN table)
  • NAME (String, e.g. “Name”)
  • VALUE (String, e.g. “Duchess”)

Description

So basically, the CAT and KITTEN tables just hold IDs and some other random information. KITTEN_INFO holds the name of the kittens (among other things). And CAT_KITTEN_PLAY logs all of the times a cat plays with a kitten.

What I need, is to write a query that returns all of the CATs whose most recent play time with a male KITTEN was in a certain date range. Let’s call it Jan 1 2011 to Jan 31 2011. I also need to include the play date and name of the most recent male and female kitten the cat played with.

So Far

Below is what I have so far:

SELECT cat.*, lastMale.PLAY_TIME maleTime, lastFemale.PLAY_TIME femaleTime, maleName.VALUE male, femaleName.VALUE female
FROM CAT cat
LEFT JOIN CAT_KITTEN_PLAY lastMale ON lastMale.CAT_ID = cat.CAT_ID 
                                  AND lastMale.GENDER = 'M'
LEFT JOIN CAT_KITTEN_PLAY lastFemale ON lastFemale.CAT_ID = cat.CAT_ID 
                                    AND lastFemale.GENDER = 'F'
LEFT JOIN KITTEN_INFO femaleName ON femaleName.KITTEN_ID = lastFemale.KITTEN_ID 
                                AND maleName.NAME = 'Name'
LEFT JOIN KITTEN_INFO maleName ON maleName.KITTEN_ID = lastMale.KITTEN_ID 
                              AND femaleName.NAME = 'Name'
    WHERE lastMale.PLAY_TIME BETWEEN '01-JAN-2011 12:00:00 AM'
                                 AND '31-JAN-2011 11:59:59 PM'

Problems

This does not account for the fact that a cat may have played with a make/female kitten more than once. So, I’d want to add “AND lastMale.PLAY_TIME = (SELECT MAX(PLAY_TIME) FROM CAT_KITTEN_PLAY WHERE CAT_ID = cat.ID AND KITTEN_GENDER = ‘M’)” onto the first join, and a similar one to the second join. But subqueries are not allowed on joins.

Any thoughts? Note that a cat may have never played with a female kitten. But the cat should still be included if they meet the criteria (hence the left joins).

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1 Answer

  1. Editorial Team

    Analytic functions are probably the best answer to your problem:

    SELECT DISTINCT
       cat.*, 
       first_value(lastMale.PLAY_TIME) 
          over (partition by cat.id 
                order by lastMale.PLAY_TIME desc nulls last) maleTime,
       first_value(lastFemale.PLAY_TIME) 
          over (partition by cat.id 
                order by lastFemale.PLAY_TIME desc nulls last) femaleTime,
       first_value(maleName.VALUE)  
          over (partition by cat.id 
                order by lastMale.PLAY_TIME desc nulls last) male,
       first_value(femaleName.VALUE)  
          over (partition by cat.id 
                order by lastFemale.PLAY_TIME desc nulls last) female
...
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