Saturday, May 28, 2011

ACID Rules in Sql Server


ACID Rules

ACID Rules:- It is a concept for evaluation of databases and their architecture.

A:- (Atomicity) – Atomicity  states the principle of  All or none. This means that either all the SQL Statements within the transaction will be executed or no Sql statement will be executed.

C:- Consistency:- Consistency states that only valid data will be written into the database. That means if any Sql transaction violets the rules or constraints define on the database to make it consistent, then all the statements within the transaction will be Rollback. Or in other words the whole transaction will be rolled back.

I:- Isolation :- The Isolation state that if multiple transaction try to work on the database at the same time,then these transaction will not interfere with each other. It means the second transaction will not work unless and until the previous transaction completes its work and the work is commited.

D:- Durability:- Durability states that once the transaction is committed, then the database should not be lost in case of Software failures or hardware failures. Durability is maintained with the help of the  database backups and transaction logs. 

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