DROP CONSTRAINT

SQL DROP CONSTRAINT Keyword

The DROP CONSTRAINT command is used to delete a UNIQUE, PRIMARY KEY, FOREIGN KEY, or CHECK constraint from a table.

SQL DROP CONSTRAINT Syntax

ALTER TABLE table_name
DROP CONSTRAINT constraint_name;

ALTER TABLE table_name

DROP CONSTRAINT constraint_name;

SQL DROP a UNIQUE Constraint

ALTER TABLE Patients
DROP CONSTRAINT UC_Patients;

ALTER TABLE Patients

DROP CONSTRAINT UC_Patients;

Note: This syntax is not supported in SQLite, including our TechKubo playground. SQLite does not support dropping constraints after table creation.

SQL DROP a PRIMARY KEY Constraint

ALTER TABLE Doctors
DROP CONSTRAINT PK_Doctors;

ALTER TABLE Doctors

DROP CONSTRAINT PK_Doctors;

Note: Not supported in SQLite. Primary keys cannot be dropped using ALTER TABLE.

SQL DROP a FOREIGN KEY Constraint

ALTER TABLE Appointments
DROP CONSTRAINT FK_DoctorAppointment;

ALTER TABLE Appointments

DROP CONSTRAINT FK_DoctorAppointment;

Note: Not supported in SQLite. Foreign keys cannot be dropped using ALTER TABLE.

SQL DROP a CHECK Constraint

ALTER TABLE MedicalRecords
DROP CONSTRAINT CHK_Temperature;

ALTER TABLE MedicalRecords

DROP CONSTRAINT CHK_Temperature;

Note: Not supported in SQLite. Check constraints cannot be dropped using ALTER TABLE.

SQL DROP CONSTRAINT Labs