difference between relational integrity and data intigrity

[Former Member]

hi

could anybody tell me

what is the difference between

relational integrity and data intigrity

tahnx

kals.

[sourabhshah]

hi,

Data Integrity

Data integrity means, in part, that you can correctly and consistently navigate and manipulate the tables in the database. There are two basic rules to ensure data integrity; entity integrity and referential integrity.

The entity integrity rule states that the value of the primary key can never be a null value (a null value is one that has no value and is not the same as a blank). Because a primary key is used to identify a unique row in a relational table, its value must always be specified and should never be unknown. The integrity rule requires that insert, update, and delete operations maintain the uniqueness and existence of all primary keys.

The referential integrity rule states that if a relational table has a foreign key, then every value of the foreign key must either be null or match the values in the relational table in which that foreign key is a primary key.

What is a Relational Integrity?

A relational database contains tables of data which are related to each other. For example, articles are related to the author who wrote them, and conversely, authors are related to the articles they wrote. (Sounds obvious, and it is.) That's the relational part.

When we work with a relational database, we naturally expect that data in related tables stay related. For example, articles written by MartinB should always be related to MartinB and never be confused with articles written by any other author. That's the integrity part.

Relational Integrity is also called Referential Integrity, perhaps because the mechanism for ensuring integrity is implemented by the way the tables reference each other. Both terms are okay with me. I usually just say RI anyway.

Regards,

Sourabh