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SQL FOREIGN KEY Constraint

SQL FOREIGN KEY constraint represents relationship between tables. A Foreign Key is a column(s) whose values are derived from the PRIMARY KEY or UNIQUE KEY of some other table. If you want to associate records of...

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SQL PRIMARY KEY Constraint

SQL PRIMARY KEY constraint uniquely identifies each row in a database table. A primary key column cannot have NULL values. A table can have only one primary key with single or multiple fields. Primary...