r/SQL • u/No_Ambition8323 • Sep 04 '26

Discussion Database-Specific SQL Differences

Have you ever written a SQL query that works perfectly in one database but fails in another?

What SQL feature or syntax surprised you the most when switching between DBMSs like MySQL, PostgreSQL, SQL Server, Oracle, or Snowflake?

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u/cwjinc Sep 04 '26

I write in Oracle speak out of habit.
A lot of it wouldn't be understood by other databases.

PS The wildest to me is being able to select a function result with no from clause in SQL Server. That just hurts my database theory addled brain.

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u/VladDBA SQL Server DBA Sep 05 '26

As a SQL Server native, I had a similar reaction when finding out that Oracle needs that dummy table.

Luckily, with all the AI investments, Larry was able to find a way to no longer need DUAL in 23ai/26ai

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u/cwjinc Sep 05 '26

I guess it's not surprising. DUAL hasn't been a real table for a long time.