SQL Logical Operators

SQL Logical Operator

In SQL, Logical Operators are used to combine multiple conditions within the WHERE clause. These operators help retrieve records that meet specific complex criteria, improving data filtering in your queries.

What Are Logical Operators?

Logical operators evaluate conditions and return TRUE, FALSE, or UNKNOWN for each row. They are used to control which rows appear in the final result set based on one or more logical conditions.

Types of SQL Logical Operators

Operator	Description
AND	Returns TRUE only if all conditions are true
OR	Returns TRUE if any condition is true
NOT	Reverses the result of a condition

Logical AND Operator

Returns rows only when all conditions are satisfied.

Customer Table

Customer ID	Name	Postal Code	Country
2	Shiva	05021	America
4	Hanuman	05023	Mexico
1	Dhruva	05026	Japan
3	Ganesh	05024	Mexico

Example:

SELECT *
FROM Customer
WHERE Country = 'Mexico' AND CustomerID > 2;

Output:

Customer ID	Name	Postal Code	Country
4	Hanuman	05023	Mexico
3	Ganesh	05024	Mexico

Explanation: Shows customers from Mexico whose CustomerID is greater than 2.

Logical OR Operator

Returns rows if at least one condition is true.

Customer Table

Customer ID	Name	City	Country
1	James	Paris	Germany
2	William	Lyon	Italy
3	Daniel	Berlin	France
4	Oliver	Marseille	Germany

Example:

SELECT *
FROM Customer
WHERE Country = 'Germany' OR City = 'Berlin';

Output:

Customer ID	Name	City	Country
1	James	Paris	Germany
3	Daniel	Berlin	France
4	Oliver	Marseille	Germany

Explanation: Displays records where the country is Germany or the city is Berlin.

Logical NOT Operator

Returns rows where the condition is NOT true.

Customer Table

ID	Name	City	Country
1	James	Paris	Germany
2	Daniel	Berlin	Italy
3	Oliver	Marseille	Germany
4	Rose	Belgium	France

Example:

SELECT *
FROM Customer
WHERE NOT Country = 'Germany';

Output:

ID	Name	City	Country
2	Daniel	Berlin	Italy
4	Rose	Belgium	France

Explanation: Displays customers who do not belong to Germany.

Key Point

Use AND when all conditions must be true.

Use OR when at least one condition must be true.

Use NOT to exclude specific records.

Logical operators are essential for writing complex and precise SQL queries.