1.

What is constraints and its types in DBMS?

Answer»

Constraints are set of rules USED to restrict the type of data that can go into a table, to preserve the accuracy and integrity of the RECORDS internal the table.

The different TYPES of constraints in DBMS are as follows:-
  • NOT NULL:-it makes sure that column does not hold a NULL value.
  • UNIQUE:- It INVOKES a column to have a UNIQUE value
  • DEFAULT:-gives the default value to the column
  • CHECK:-specify the range of values for a column
  • Key Constraints –
  • PRIMARY KEY:-it diagnose each and every record in a table
  • FOREIGN KEY:- it points to the primary key of any other table.


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