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Asked: 2026-05-15T08:43:55+00:00

I am curious on the most efficient way to query exclusion on sql. E.g.

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I am curious on the most efficient way to query exclusion on sql. E.g. There are 2 tables (tableA and tableB) which can be joined on 1 column (col1). I want to display the data of tableA for all the rows which col1 does not exist in tableB.

(So, in other words, tableB contains a subset of col1 of tableA. And I want to display tableA without the data that exists in tableB)

Let’s say tableB has 100 rows while tableA is gigantic (more than 1M rows). I know ‘Not in (not exists)’ can be used but perhaps there are more efficient ways (less comp. time) to do it.? I don’t maybe with outer joins?

Code snippets and comments are much appreciated.

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1 Answer

  1. Editorial Team

    Depends on the RDBMS. For Microsoft SQL Server NOT EXISTS is preferred to the OUTER JOIN as it can use the more efficient Anti-Semi join.

    For Oracle Minus is apparently preferred to NOT EXISTS (where suitable)

    You would need to look at the execution plans and decide.

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