Data Integrity:- It refers to the consistency and accuracy
of data that is stored in the data base.
Enforcing the Data Integrity ensures the quality of the data
base.
Three types of Data Integrity
- Domain or Column Integrity
- Entity or Table Integrity
- Referential integrity
Domain Integrity:-
Specifies a set of data values that are
valid for a column and determine
whether to allow null values. Domain
Integrity is often enforced by using validity checking and can be enforced by
restricting the data type, format, or range of possible values allowed in a column.
Entity Integrity:-
It requires all rows in a table have a
unique identifier, known as primary key value. Whether Primary key value can be
changed, or whether the whole row can be deleted, depends on the level of
integrity required between the primary key any other table.
Referential Integrity:-
It ensures, that relationship among
the primary keys and foreign keys are always maintained. A row in a reference
table can not be deleted, nor can the primary key can changed, if the foreign
key refers to the row, unless the cascade action is permitted. You can define
referential integrity relationships within the same table or between separate tables.
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