SQL WHERE Clause - Filtering Examples

Comparison Operators in WHERE

Comparison operators compare column values to constants or other columns.

Common operators include =, <, >, <=, >=, and <> (not equal).

• Example: WHERE age > 30
• Example: WHERE status = 'active'

Logical Operators for Multiple Conditions

Logical operators combine multiple conditions in the WHERE clause.

AND requires all conditions to be true, OR requires at least one, and NOT negates a condition.

• Example: WHERE age > 25 AND city = 'New York'
• Example: WHERE status = 'active' OR status = 'pending'
• Example: WHERE NOT department = 'Sales'

Pattern Matching with LIKE

The LIKE operator filters text columns using patterns with wildcards.

The % wildcard matches zero or more characters, and _ matches exactly one character.

• Example: WHERE name LIKE 'J%' finds names starting with 'J'.
• Example: WHERE code LIKE '_23' finds codes with any first character followed by '23'.

Filtering Examples

Let's explore practical examples using the WHERE clause to filter data.