AND / OR Operators in SQL

The AND operator is used when all conditions in a query must be satisfied.

SELECT *
FROM Students
WHERE age > 18
AND course = 'Python';

A record must satisfy both conditions to be returned.

The OR operator is used when at least one condition must be true.

SELECT *
FROM Students
WHERE course = 'Python'
OR course = 'Java';

A student can match either Python or Java.

SELECT column_name
FROM table_name
WHERE condition1
AND condition2;

SELECT column_name
FROM table_name
WHERE condition1
OR condition2;

SELECT *
FROM Students
WHERE age > 18
AND age < 25;

This returns students whose age is greater than 18 and less than 25.

SELECT *
FROM Students
WHERE city = 'Patna'
AND course = 'Python';

This returns students who are from Patna and are enrolled in Python.

SELECT *
FROM Students
WHERE age >= 18
AND fee > 5000;

Both conditions must be satisfied.

SELECT *
FROM Students
WHERE age >= 18
AND course = 'Python'
AND city = 'Patna';

All three conditions must be true.

SELECT *
FROM Students
WHERE course = 'Python'
OR course = 'Java';

This returns students enrolled in either Python or Java.

SELECT *
FROM Students
WHERE course = 'Python'
OR course = 'Java'
OR course = 'PHP';

A record is returned if its course matches any one of these three values.

Suppose we have:

Query:

SELECT *
FROM Students
WHERE age >= 18
AND course = 'Python';

Only Rahul satisfies both conditions.

Using the same data:

SELECT *
FROM Students
WHERE course = 'Python'
OR course = 'Java';

Rahul, Priya, and Amit can be returned because their course is either Python or Java.

AND is frequently used together with WHERE.

SELECT name, course
FROM Students
WHERE age > 18
AND city = 'Patna';

SELECT name, course
FROM Students
WHERE city = 'Patna'
OR city = 'Delhi';

This returns students from either Patna or Delhi.

AND and OR can be used in the same query.

SELECT *
FROM Students
WHERE age > 18
AND course = 'Python'
OR city = 'Patna';

For complex conditions, parentheses should be used to make the intended logic clear.

Parentheses allow you to group conditions.

SELECT *
FROM Students
WHERE age > 18
AND (course = 'Python' OR course = 'Java');

This means:

• Age must be greater than 18.
• Course must be either Python or Java.

SELECT *
FROM Students
WHERE city = 'Patna'
AND (course = 'Python' OR course = 'Java');

This finds students from Patna who are enrolled in either Python or Java.

SELECT *
FROM Students
WHERE age >= 18
AND fee > 5000
AND city = 'Patna'
AND course = 'Python';

Every condition must be satisfied.

SELECT *
FROM Students
WHERE city = 'Patna'
OR city = 'Delhi'
OR city = 'Mumbai';

The record can match any one of the three cities.

SELECT *
FROM Students
WHERE age >= 18
AND age <= 25;

This returns students whose age is from 18 through 25.

SELECT *
FROM Students
WHERE age < 18
OR age > 60;

This returns records where age is either below 18 or above 60.

SELECT *
FROM Students
WHERE name LIKE 'A%'
AND course = 'Python';

This finds students whose names start with A and whose course is Python.

SELECT *
FROM Students
WHERE name LIKE 'A%'
OR name LIKE 'R%';

This finds students whose names start with A or R.

SELECT *
FROM Students
WHERE course IN ('Python', 'Java')
AND age >= 18;

This finds students who are enrolled in Python or Java and are at least 18 years old.

SELECT *
FROM Students
WHERE city IN ('Patna', 'Delhi')
OR course = 'Python';

A student is returned if they are from Patna or Delhi, or if their course is Python.

SELECT *
FROM Students
WHERE age BETWEEN 18 AND 25
AND course = 'Python';

This finds Python students whose age is between 18 and 25.

SELECT name, course, fee
FROM Students
WHERE age >= 18
AND (course = 'Python' OR course = 'Java')
ORDER BY fee DESC;

The filtered results are sorted by fee from highest to lowest.

Suppose an institute wants students who:

• Are at least 18 years old.
• Are enrolled in Python or Java.
• Have paid more than ₹5,000.

Query:

SELECT *
FROM Students
WHERE age >= 18
AND (course = 'Python' OR course = 'Java')
AND fee > 5000;

SELECT name, age, course, city, fee
FROM Students
WHERE age >= 18
AND (course = 'Python' OR course = 'Java')
AND (city = 'Patna' OR city = 'Delhi')
AND fee > 5000
ORDER BY fee DESC;

This query:

• Finds students aged 18 or above.
• Allows Python or Java courses.
• Allows students from Patna or Delhi.
• Requires a fee greater than 5000.
• Sorts the result by fee in descending order.