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WHERE Filters

Common predicates, BETWEEN/IN/LIKE/IS NULL and sargability notes.

What you’ll learn

Common predicates: =, <>, BETWEEN, IN, LIKE, IS NULL.
Sargability basics (avoid wrapping indexed columns).

SELECT *
FROM dbo.Products
WHERE Price BETWEEN 10 AND 20
  AND CategoryID IN (1,2,3)
  AND Discontinued = 0
  AND Name LIKE N'%Widget%'
  AND Color IS NOT NULL;

Notes

LIKE '%prefix%' disables seeks; try LIKE N'prefix%' when possible.
Avoid WHERE YEAR(OrderDate)=2025; prefer OrderDate >= '2025-01-01' AND OrderDate < '2026-01-01'.