|SQL - Structured Query Language|
Unique Key Constraint
Unique Constraint can define with one column or set of columns that used to identify a Record and to avoid duplicate Records of Table in the Relational Database. Unique Constraint is accepting Null Data. Each Table can define with one or more than one Unique Constraint. Unique Constraint is helps to define Alternative Key.
The following SQL Statements are used to create DEPT and EMP Tables with set of constraints.
More Reference URL: https://data-e-education.com/RDBMS/Key_Integrity_Constraints.php
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