SQL ADD CONSTRAINT Keyword

Concept visual

SQL ADD CONSTRAINT Keyword

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ADD CONSTRAINT Keyword

Add Constraint

The ADD CONSTRAINT

command is used to create a constraint after a table is already created. The following SQL adds a constraint named "PK_Person" that is a PRIMARY KEY constraint on multiple columns (ID and LastName):

Example

ALTER TABLE Persons

ADD CONSTRAINT PK_Person PRIMARY KEY (ID,LastName);

SQL ADD CONSTRAINT Keyword

Concept visual

SQL ADD CONSTRAINT Keyword

Pointer walk

two pointers

left=0

right=6

1

3

Start at both ends

ADD CONSTRAINT Keyword

Add Constraint

The ADD CONSTRAINT

command is used to create a constraint after a table is already created. The following SQL adds a constraint named "PK_Person" that is a PRIMARY KEY constraint on multiple columns (ID and LastName):

Example

ALTER TABLE Persons

ADD CONSTRAINT PK_Person PRIMARY KEY (ID,LastName);

SQL ADD CONSTRAINT Keyword

SQL ADD CONSTRAINT Keyword

ADD CONSTRAINT Keyword

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Add Constraint

The ADD CONSTRAINT

Example

ALTER TABLE Persons

Previous

Next

SQL ADD CONSTRAINT Keyword

SQL ADD CONSTRAINT Keyword

ADD CONSTRAINT Keyword

Previous

Next

Add Constraint

The ADD CONSTRAINT

Example

ALTER TABLE Persons

Previous

Next