WHERE Clause & Operators

WHERE Clause & Operators — Deep dive into WHERE clause operators: comparison, logical, pattern matching, and range filters. The guide walks through Comparison Operators, Logical Operators (AND, OR, NOT), Range (BETWEEN) & List (IN), NULL Handling. Use = for equality, <> or != for inequality, > and < for greater/less than, >= and <= for greater/less or equal. String comparisons may be case-sensitive depending on the database collation. Numeric comparisons work as expected with integers, decimals, and floats. AND combines conditions where ALL must be true. OR requires ANY condition to be true. NOT negates a condition. AND has higher precedence than OR, so use parentheses to control evaluation order: WHERE (condition1 OR condition2) AND condition3. The guide is organized into 4 sections that build on each other, each pairing a prose explanation with real SQL you can run as-is. Related guides: SQL Introduction, SELECT Statement, SQL JOINs, GROUP BY & Aggregation, Subqueries & CTEs.