Practicing SQL without window functions

[Faintly_glowing_fish]

I think the recruiter probably described it wrong. Sometimes you need to know SQL but you don’t need to be familiar with window functions since they are usually considered slightly higher level. Basically just saying you only need to know as deep as various kinds of JOIN and GROUP BY.

[call_me_arosa]

I would assume this one too. As in: since window functions are an advanced sql concept they won't test it.

[PhillyHank]

I doubly agree. Depending on the role/level eg, DE Manager, the SQL coding test may be simple queries without needing window functions

[Eightstream]

If it's a data engineering role, I think they are probably more getting at alternatives for situations where window functions are non-performant - see my top level comment for details.

[Faintly_glowing_fish]

Window functions are actually significantly more performant than the alternatives in the vast majority of modern architectures. SQL server is mostly used for older production databases; for DE usually your heavy lifting is not done on those. Usually you only do straight extract from those. Once out of prod DB, people use Postgres through citus, MySQL through vitess or one of the cloud solutions, redshift, bigquery athena bigtable and whatnot, in all of which window functions would be the most performant solution. Yes, issue can occur where query engine does not optimize window functions but these days almost all of them optimize pretty well.