WHERE Clause & Filtering

Column Aliasing & Expressions

CASE Statements & Conditional Logic

Write a query using all six comparison operators

Fix a broken query with AND/OR precedence issues

Rewrite a NOT IN query with NOT EXISTS

Convert a leading-wildcard LIKE to a sargable form

What is three-valued logic and how does it affect NULL comparisons?

When does NOT IN return zero rows unexpectedly?

What makes a LIKE pattern sargable?