What are constraints

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Constraints are rules that are applied to the data in a database to ensure its integrity and consistency.

Constraints define the limits or conditions that must be met for data to be valid.
They can be applied to individual columns or entire tables.
Common types of constraints include primary key, foreign key, unique, and check constraints.
Primary key constraints ensure that each row in a table is uniquely identified.
Foreign key constraints enforce referential integrity between tables.
Unique constraints ensure that values in a column or set of columns are unique.
Check constraints define conditions that must be met for data to be inserted or updated.
Constraints help maintain data integrity and prevent inconsistencies or errors in the database.

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