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WHERE Clause
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The WHERE clause filters rows returned by a SQL query based on specific search conditions. Only rows that evaluate to TRUE for the condition are included in the result set.
1. Syntax
sql
SELECT column1, column2
FROM table_name
WHERE condition;
2. Comparison Operators
| Operator | Description | Example |
| :--- | :--- | :--- |
| = | Equal to | WHERE department = 'Sales' |
| <> or != | Not equal to | WHERE status != 'Inactive' |
| > | Greater than | WHERE salary > 80000 |
| < | Less than | WHERE age < 30 |
| >= | Greater than or equal | WHERE rating >= 4.5 |
| <= | Less than or equal | WHERE price <= 100 |
3. Logical Operators: AND, OR, NOT
Combine multiple search criteria using logical operators:
sql
-- Filter for Engineering department AND high salary
SELECT first_name, last_name, salary
FROM employees
WHERE department = 'Engineering' AND salary >= 100000;
-- Filter for Sales OR Marketing departments
SELECT first_name, last_name, department
FROM employees
WHERE department = 'Sales' OR department = 'Marketing';