IS NOT NULL

SQL IS NOT NULL Keyword

The IS NOT NULL condition checks for columns that have actual values—not empty or missing. This is helpful when filtering only complete records or valid references.

SQL IS NOT NULL Syntax

SELECT column1, column2, ...
FROM table_name
WHERE column_name IS NOT NULL;

SQL IS NOT NULL Appointments with Doctor Example

This query returns all appointments that are linked to a doctor:

SELECT appointment_id, doctor_id, appointment_date
FROM Appointments
WHERE doctor_id IS NOT NULL;

SQL IS NOT NULL with JOIN Example

This query returns doctor names and their assigned appointments (only if doctor_id is present):

SELECT Doctors.first_name, Doctors.last_name, Appointments.appointment_date
FROM Doctors
JOIN Appointments ON Doctors.doctor_id = Appointments.doctor_id
WHERE Appointments.doctor_id IS NOT NULL;

SQL IS NOT NULL Labs