Skip to main content

What is ACID Property or Properties of the Relational tables?

The ACID rules of transaction in any database ensure the reliability of data in all transactions in the database.

Atomicity

Atomicity shows the ability of database to assure that either all tasks of a transaction are performed or none of them. In other words database modifications must follow an all or nothing. Each transaction is said to be atomic if when one part of the transaction fails the entire transaction fails.

Consistency

Consistency assure that database remain consistent state before the transaction and after the transaction is over.
For Example: An application transfer fund from one account to other account , the consistency property ensure that the total value of transaction should be same in both account at the start and end of transaction.  

Isolation 

Isolation assure that other operation can't be performed in an intermediate state during a transaction. As a result, transactions that run concurrently appear to be serialized.
For Example : DK Start transaction against the database at same time Singh issues the different transaction against same database, both transaction should operate on database in an isolated manner. The database perform DK's entire transaction or Singh's entire transaction but not together.

Durability 

Durability  is responsible to notify the transaction is succeed, the transaction will persist, not undone. It will survive system failure and the database system has checked the integrity constraints and no need to abort the transaction.

Popular posts from this blog

Query to find stored procedures by nested stored procedure name

Problem: Suppose we have a stored procedure which has been used in several stored procedure, I mean stored procedure usp_proc1 is nested in many stored procedures like below
BEGIN DECLARE@ResultTABLE ( IDINT, NAMEVARCHAR(50), [ADDRESS]VARCHAR(255) ) INSERTINTO@Result EXECusp_proc1@Name='codefari' END
So I want to find all those queries who containing usp_proc1
Solution: There is a lot of solutions, I'm giving some of them below. If you want to get the only name of the stored procedures then use the following query. Using join query on system tables syscomments and sysobjects we can get the stored procedures name which containing the particular table, nested procs or any other string.
SELECTDISTINCTo.name FROMsyscommentss INNERJOINsysobjectsoONs.id=o.id

Check for changes to an SQL Server table?

Problem: Suppose your team is working on the under-development project so it might be possible continuous work on the database and perform changes in Table, Stored procedure as per requirement, and daily you have to update the testing server database as per changes are done in developing server database then how it is possible to trace those changes. There are a lot of solutions for this problem which is listed below Solution 1: For SQL Server 2000, 2005 and above use the CHECKSUM command SELECTCHECKSUM_AGG(BINARY_CHECKSUM(*))FROMYour_Table_NameWITH (NOLOCK); That will return the same number each time its run as long as the table contents haven't changed. Unfortunately CHECKSUM does not work always properly to detect changes. It is only a primitive checksum and no CRC calculation. Therefore you can't use it to detect all changes, e. g. symmetrical changes result in the same CHECKSUM! Solution 2: 1.Run the following query. Before executing query replace DB_Name with your database name…

Merge and Merge join transformation in SSIS

MERGE TRANSFORMATION
Using Merge Transformation we can combine two sorted data-set into single data-set basically Merge Transformation used to combines rows from two sorted data flows into one sorted data flow. Following tasks you may perform using Merge Transformation: 1.Suppose we have a scenario like, we need to merge data from a database table and excel means we want to merge data from two different data sources. For such type of scenario, you can use Merge Transformation. 2.If we want to merge data from two same structured tables but exists two different servers. 3.Sometimes we get an error due to data in a row, after correcting errors in the data we can re-merge rows easily. See below explanations may help you to understand Merge Transformation: I do evaluate here, you already know about the data source, data conversion, data flow, task flow, control flow etc. Note:Before Merge transformation, we need to sort the data using Sort Transformation. After sorting data add data path to Merge…