Tuesday, 4 February 2020

Integrity Constraints


Integrity Constraints

? Database objects allow fields to be defined that are calculated by any specified method
(and not stored in the database).
? They allow referential integrity (the relationships between objects that must be maintained
(e.g. invoice master/detail) to be defined in a database-independent way, they allow a set
Database Management Systems/Managing Database
Notes of valid values to be defined for a field and verify field validation against that list
automatically, they allow serial number fields to be automatically assigned correct values,
and much more.

Column Level Constraints: If the constraints are defined along with the column definition, it is
called as a column level constraint.
Foreign Key: Foreign keys represent relationships between tables.
Primary Key: A primary key is one or more columns in a table used to uniquely identify each
row in the table.
Table Level Constraints: If the data constraint attached to a specific cell in a table references the
contents of another cell in the table then the user will have to use table level constraints.

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