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SQL•SQL References

SQL DROP CONSTRAINT Keyword

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SQL DROP CONSTRAINT Keyword

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DROP CONSTRAINT Keyword

Drop Constraint

The DROP CONSTRAINT

command is used to delete a UNIQUE, PRIMARY KEY, FOREIGN KEY, or CHECK constraint.

DROP a UNIQUE Constraint

To drop a UNIQUE constraint, use the following SQL:

Formula

SQL Server / Oracle / MS Access:

ALTER TABLE Persons

DROP CONSTRAINT UC_Person;

MySQL:

ALTER TABLE Persons

DROP INDEX UC_Person;

DROP a PRIMARY KEY Constraint

To drop a PRIMARY KEY constraint, use the following SQL:

Formula

SQL Server / Oracle / MS Access:

ALTER TABLE Persons

DROP CONSTRAINT PK_Person;

MySQL:

ALTER TABLE Persons

DROP PRIMARY KEY;

DROP a FOREIGN KEY Constraint

To drop a FOREIGN KEY constraint, use the following SQL:

Formula

SQL Server / Oracle / MS Access:

ALTER TABLE Orders

DROP CONSTRAINT FK_PersonOrder;

MySQL:

ALTER TABLE Orders

DROP FOREIGN KEY FK_PersonOrder;

DROP a CHECK Constraint

To drop a CHECK constraint, use the following SQL:

Formula

SQL Server / Oracle / MS Access:

ALTER TABLE Persons

DROP CONSTRAINT CHK_PersonAge;

MySQL:

ALTER TABLE Persons

DROP CHECK CHK_PersonAge;

SQL DROP CONSTRAINT Keyword

Concept visual

SQL DROP CONSTRAINT Keyword

Pointer walk

two pointers

left=0

right=6

1

3

Start at both ends

DROP CONSTRAINT Keyword

Drop Constraint

The DROP CONSTRAINT

command is used to delete a UNIQUE, PRIMARY KEY, FOREIGN KEY, or CHECK constraint.

DROP a UNIQUE Constraint

To drop a UNIQUE constraint, use the following SQL:

Formula

SQL Server / Oracle / MS Access:

ALTER TABLE Persons

DROP CONSTRAINT UC_Person;

MySQL:

ALTER TABLE Persons

DROP INDEX UC_Person;

DROP a PRIMARY KEY Constraint

To drop a PRIMARY KEY constraint, use the following SQL:

Formula

SQL Server / Oracle / MS Access:

ALTER TABLE Persons

DROP CONSTRAINT PK_Person;

MySQL:

ALTER TABLE Persons

DROP PRIMARY KEY;

DROP a FOREIGN KEY Constraint

To drop a FOREIGN KEY constraint, use the following SQL:

Formula

SQL Server / Oracle / MS Access:

ALTER TABLE Orders

DROP CONSTRAINT FK_PersonOrder;

MySQL:

ALTER TABLE Orders

DROP FOREIGN KEY FK_PersonOrder;

DROP a CHECK Constraint

To drop a CHECK constraint, use the following SQL:

Formula

SQL Server / Oracle / MS Access:

ALTER TABLE Persons

DROP CONSTRAINT CHK_PersonAge;

MySQL:

ALTER TABLE Persons

DROP CHECK CHK_PersonAge;

SQL DROP CONSTRAINT Keyword

SQL DROP CONSTRAINT Keyword

DROP CONSTRAINT Keyword

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Drop Constraint

The DROP CONSTRAINT

DROP a UNIQUE Constraint

ALTER TABLE Persons

MySQL:

ALTER TABLE Persons

DROP a PRIMARY KEY Constraint

ALTER TABLE Persons

MySQL:

ALTER TABLE Persons

DROP a FOREIGN KEY Constraint

ALTER TABLE Orders

MySQL:

ALTER TABLE Orders

DROP a CHECK Constraint

ALTER TABLE Persons

MySQL:

ALTER TABLE Persons

Previous

Next

SQL DROP CONSTRAINT Keyword

SQL DROP CONSTRAINT Keyword

DROP CONSTRAINT Keyword

Previous

Next

Drop Constraint

The DROP CONSTRAINT

DROP a UNIQUE Constraint

ALTER TABLE Persons

MySQL:

ALTER TABLE Persons

DROP a PRIMARY KEY Constraint

ALTER TABLE Persons

MySQL:

ALTER TABLE Persons

DROP a FOREIGN KEY Constraint

ALTER TABLE Orders

MySQL:

ALTER TABLE Orders

DROP a CHECK Constraint

ALTER TABLE Persons

MySQL:

ALTER TABLE Persons

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