SQL Constraints :-

  • NOT NULL - Indicates that a column cannot store NULL value

  • UNIQUE - Ensures that each row for a column must have a unique value

  • PRIMARY KEY - A combination of a NOT NULL and UNIQUE. Ensures that a column (or combination of two or more columns) have a unique identity which helps to find a particular record in a table more easily and quickly

  • FOREIGN KEY - Ensure the referential integrity of the data in one table to match values in another table

  • CHECK - Ensures that the value in a column meets a specific condition

  • DEFAULT - Specifies a default value for a column.

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