what is Constraint? How many types of constraints in SQL ?

Answer Posted / ramesh.n

constraints are the restrictions or limitations that are
being imposed on the columns of a table to validate the data
either for insertion or updation constraints can be imposed
either during the process of table creation of a level.

There are 8 types of constraints
1.unique
2.Not null
3.Primary key
4.Check
5.Default
6.Foreign key
7.composite primary key
8.composite unique key

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