Data integrity limits restriction among the values the database

Define Relational Database Model –

A relational Database is a set of inter-related tables which is called relations.

to the given criteria.

Data structure - The data structure model defines the inter-related data.

Table name: Student

Fields -> Student_id student_name student_type

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Figure 1- Table Name 1- Student

For example: If the fields’ value set Integer value then the attribute value’s inserted should not be double.

Entity Integrity – To define each row in the table where no duplication occurs means non redundancy of data in the table.

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Referential Integrity- Set of fields in one relation that is used to `refer’ to a tuple in another relation (i.e. - Primary Key) which is known as foreign key of the table. A foreign key value can be NULL

For Example – Student type is the Primary Key of the table- 2 but Student Type in table -1 is not Foreign Key referring to Student. If all Foreign Key Constraints are not enforced, referential integrity is not achieved.

Syntax: update Table_ name set Field_name1 =”value”.

DELETE- removes the selected values, rows from the table.

Syntax: SELECT Field_name1 FROM Table_name1 INTERSECT SELECT FROM Field_name1 FROM Table_name2.

UNION - merging data

Syntax: Select tablename.field_name1 from table_name1, table_name2 where table_name1.field_name1 = table_name2.field_name1

ORDERING – Arranging the rows based upon the criteria.

The given database does not satisfy the properties of a relational database.

The given Database does not support the CODD’s twelve rules that make a RDMS

In Table - student Type, if we consider the student_type Field as primary key as there is no duplication of data.

But in relational database model the Tables are inter-related but no other table used as Foreign Key of the student Type table as there is duplication of the data in student_type field of another Table.It does not Follow the Referential Integrity rules.

http://www.colorado.edu/ibs/pubs/pac/pac2003-0002.pdf

2). R. Ramakrishnan and J. Gehrk

http://www.wonko.info/ipt/iis/sql/sql3.htm

4). Amitabh Trehan (2003, 22^th August)