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Databases

Posted by snailort
snailort
1,561 Points

SQL

Having a hard time wrapping my brain around this.

Suppose I have a table like this

1 Answer

Steven Parker
Steven Parker
231,269 Points
Steven Parker
Steven Parker
231,269 Points

The result set will have a separate row for each unique combination of items being grouped by. So don't include the date in the grouping:

SELECT name, date, MAX(amount) 
FROM sample
GROUP BY name
snailort
snailort
1,561 Points

Thanks Steven! The issue with that is when I try and run this, I receive the following error:

ERROR: column "sample.date" must appear in the GROUP BY clause or be used in an aggregate function

I'm assuming that is where a subquery comes in, but that is where I'm having a hard time seeing how that would work.

Steven Parker
Steven Parker
231,269 Points
Steven Parker
Steven Parker
231,269 Points

If you are using a database engine that does not allow you to select a column that isn't being grouped or aggregated (not an issue with SQLite), you could use your subquery idea:

SELECT name, date, amount
FROM sample s
WHERE amount = (SELECT MAX(amount) from sample WHERE name = s.name)
snailort
snailort
1,561 Points

Sweet, that second one did it! Thanks so much, going to sit with this one for a bit :)