by Markus Winand.

Obfuscated Conditions

The following sections demonstrate some popular methods for obfuscating conditions. Obfuscated conditions are where clauses that are phrased in a way that prevents proper index usage. This section is a collection of anti-patterns every developer should know about and avoid.


  1. Dates — Pay special attention to DATE types

  2. Numeric Strings — Don’t mix types

  3. Combining Columns — use redundant where clauses

  4. Smart Logic — The smartest way to make SQL slow

  5. Math — Databases don’t solve equations

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Markus Winand is the SQL Renaissance Ambassador. He is on a mission to introduce developers to the evolution of SQL in the 21st century. Markus can be hired as trainer, speaker and consultant via

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