what is consistency and intergrity

Hi,

1. Can any body tell that what is consistency and intergrity in oracle with suitable examples

2. What is normalization in oracle. pls provide the solution with suitable examples.

Normalisation is a process of organising data to minimize the redundancy and remove ambiguity. It involves separating database into tables and defining relationships between the tables.

Hi Saravanan,

[B]Data consistency[/B] means the validity & accuracy of the data available in the database.
The consistency of the data is identified by the relevant changes made by the user's transactions and as well as other users transactions.

[B]Data Integrity[/B] is enforcing the business rules associated with your database and prevent the entry of invalid information into tables using integrity constraints.

In a single-user database, the user can modify data in the database without concern for other users modifying the same data at the same time. However, in a multiuser database, the statements within multiple simultaneous transactions can update the same data. Transactions executing at the same time need to produce meaningful and consistent results. Therefore, control of data concurrency and data consistency is vital in a multiuser database.

Data concurrency means that many users can access data at the same time.

Data consistency means that each user sees a consistent view of the data, including visible changes made by the user's own transactions and transactions of other users.

Example can be of bank transactions:
One person can be viewing the account to deposit the money and the other to witdraw the money.
So,here,Transactions must happen so that one follows the other in a serial order.This is guaranteed by its consistent nature.
Oracle maintains consistency by maintaining locks.

Integrity:

It is important that data adhere to a predefined set of rules, as determined by the database administrator or application developer. As an example of data integrity, consider the tables employees and departments and the business rules for the information in each of the tables, as illustrated in Figure attached

Normalization:

Basically, it's the process of efficiently organizing data in a database.
There are two goals of the normalization process: eliminate redundant data (for example, storing the same data in more than one table) and ensure data dependencies make sense (only storing related data in a table). Both of these are worthy goals as they reduce the amount of space a database consumes and ensure that data is logically stored.

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