1️⃣ Comparison Operators

Used to compare values.

=       Equal to

<>      Not equal to

!=      Not equal to (in many DBs)

>       Greater than

<       Less than

>=      Greater than or equal to

<=      Less than or equal to

2️⃣ Logical Operators

Used to combine multiple conditions.

AND

OR

NOT

3️⃣ Range Operator

BETWEEN

NOT BETWEEN

Example:

WHERE salary BETWEEN 30000 AND 60000

WHERE salary NOT BETWEEN 30000 AND 60000

4️⃣ Set Operators

IN

NOT IN

Example:

WHERE department_id IN (1, 2, 3)

WHERE department_id NOT IN (1, 2, 3)   // Meaning: Select records where department_id is NOT 1, 2, or 3.

Similar to: 

WHERE department_id <> 1 

AND department_id <> 2 

AND department_id <> 3

5️⃣ Pattern Matching Operators

LIKE

NOT LIKE

Wildcards used with LIKE:

%   (zero or more characters)

_   (exactly one character)

Example:

Examples:

Starts with 'A'

WHERE name LIKE 'A%'

Ends with 'A'

WHERE name LIKE '%A'

Contains 'A' anywhere

WHERE name LIKE '%A%'

Second letter is 'A'

WHERE name LIKE '_A%'

Exactly 5 characters

WHERE name LIKE '_____'

NOT LIKE Examples:

Does not start with 'A'

WHERE name NOT LIKE 'A%'

Does not contain 'A'

WHERE name NOT LIKE '%A%'

6️⃣ NULL Operators

IS NULL

IS NOT NULL

Example:

WHERE commission IS NULL

7️⃣ Subquery Operators

Used with subqueries.

EXISTS

NOT EXISTS

ANY

SOME

ALL

Example:

WHERE salary > ALL (SELECT salary FROM managers)

8️⃣ Boolean (Some Databases)

IS TRUE

IS FALSE

IS UNKNOWN

9️⃣ String & Other Conditional Operators (DB-specific)

Some databases support:

REGEXP / RLIKE      (pattern matching in MySQL)

ILIKE               (case-insensitive LIKE in PostgreSQL)

🔟 Arithmetic Operators (Can Be Used Inside WHERE)

+   Addition

-   Subtraction

*   Multiplication

/   Division

%   Modulus

Example:

WHERE salary * 12 > 500000

📌 Complete Operator & Keyword List (Quick View)

=, <>, !=, >, <, >=, <=

AND, OR, NOT

BETWEEN, NOT BETWEEN

IN, NOT IN

LIKE, NOT LIKE

IS NULL, IS NOT NULL

EXISTS, NOT EXISTS

ANY, SOME, ALL

IS TRUE, IS FALSE, IS UNKNOWN

REGEXP, RLIKE, ILIKE

+, -, *, /, %