SQL Interview: 77 SARGability

This is a post in the SQL Interview series. These aren’t trick or gotcha questions, they’re just questions designed to scope out a candidate’s knowledge around SQL Server and Azure SQL Database.

Section: Development Level: Medium

Question:

A DBA at your site tells you that you need to make sure your predicates are sargable.

What is SARGability?

Assume a table has a column called OrderDate and it is of date data type. There is a single column index on the column. Can you give an example of a non-sargable predicate that uses it?

Answer:

SARGability determines if a query can take advantage of indexes efficiently, particularly for filtering conditions (e.g., in WHERE, JOIN ON, HAVING, etc.).

An example of a non-sargable predicate would be wrapping a function around the column before using it:

WHERE YEAR(OrderDate) = 2025

2025-09-09