SQL Constraints, NOT NULL, UNIQUE, PRIMARY KEY, FOREIGN KEY, CHECK, DEFAULT, CREATE INDEX

SQL Constraints

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Constraints

|- CHECK

|- NOT NULL

|- UNIQUE

|- PRIMARY KEY

|- DEFAULT

|- FOREIGN KEY

|- INDEX

* These constraints are also known as Integrity Constraints.

* SQL Constraints:- Constraints are the rules and restrictions applied to the data in a table.

* NOT NULL:- Value cannot be Null in a column.

* UNIQUE:- Value cannot be the same in a column.

* PRIMARY KEY:- Used to uniquely identify a row.

* FOREIGN KEY:- References a row in another table.

* CHECK:- Satisfies a specific condition.

* DEFAULT:- Set default value.

* CREATE INDEX:- Used to speed up the reading process.

Comments

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