# Conditional expressions
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In SQL, conditional expressions are used to make decisions based on certain conditions. They allow you to control the flow of your SQL statements and return different values or perform different actions based on the evaluation of one or more conditions.

AWS Clean Rooms supports the following conditional expressions:

**Topics**
+ [CASE conditional expression](CASE_function.md)
+ [COALESCE expression](coalesce-function.md)
+ [GREATEST and LEAST expression](GREATEST_LEAST.md)
+ [IF expression](IF.md)
+ [IS\_NULL expression](IS_NULL.md)
+ [IS\_NOT\_NULL expression](IS_NOT_NULL.md)
+ [NVL and COALESCE functions](NVL_function.md)
+ [NVL2 function](NVL2.md)
+ [NULLIF function](NULLIF_function.md)