CODEWITHSUNDEEP
sqlpostgresql
Chicken Sandwich No Pickles
Chicken Sandwich No Pickles

Reputation: 3362

Confused SQL Order

I have a query that looks like this:

SELECT
    date(created_at as date) as created_date,
    id,
    count(distinct file_name) as files_total,
    null as files_error
FROM table
GROUP BY created_date, id

I do not have a columns called created_date anywhere in my table.

Why does this query work?

Created_Date

is created when taking the date of created_at, in the select part of the query.

SQL is processed in this order:

from, where, group by, having, select, order by

Group By comes before Select.

In the query above, the alias didn't come until after the group by, but for some reason, the alias works in the group by.

Why is this?

Upvotes: 2

Views: 46

Answers (1)

Pரதீப்
Pரதீப்

Reputation: 93694

You don't have a column named created_date, but you have created a alias name created_date here

date(created_at as date) as created_date,

In postgresql, alias names can be referred in Group by that is why it was working

Logically Group by clause might be processed after the select though it is not the case in all the DBMS

Upvotes: 2

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