A constraint is a rule applied on a database table.
It controls what type of data can be stored in a column.
Constraints help maintain data accuracy.
Constraints prevent invalid data from entering the database.
They protect the integrity of stored information.
Without constraints, data becomes unreliable.
Constraints can be applied at column level or table level.
They automatically enforce rules.
Common constraints include NOT NULL, UNIQUE, PRIMARY KEY, and FOREIGN KEY.
Each constraint serves a specific purpose.
Constraints are essential for safe database design.
They reduce data errors.
Every backend developer must understand constraints.