Why do you need to know the relational databases? (and of course, why you need to know the transactions as well)
The relational database exists since 1970 and has been marketed since about 1982! That is, more than 30 years of use, improves the product and offers many features for your applications! I venture to say that 80% of existing applications in the world use relational databases (and use transaction too). So knowledge it is indispensable to create great applications
Do you know what is transaction?
Relational databases have many interesting and important features! In this post I would like to highlight and explain the transaction support and ACID properties (Atomicity, Consistency, Isolation and Durability).
A transaction is operations sequence treated as a block single and indivisible (atomic) during a fault recovery and that isolate between concurrent accesses in the same mass of data. A transaction is executed in its entirety or is not executed. So, if it fails for any reason, any changes to the database that the transaction might have made are undone. This “all or nothing” property is known as Atomicity.
A transaction is a single unit, its actions can not be merged with other database operations that do not participate in the transaction. Even a single SQL command involves many separate database accesses, and a transaction can consist of multiple SQL commands. Therefore, the database management system (DBMS) needs to take special actions to ensure that transactions operate correctly, without interference from database commands running concurrently. This is the property characteristic called Isolation.
To ensure that the database system does not miss a successfully completed transaction from a later failure, the actions of a transaction must persist between failures. In addition, the results of one transaction can only be undone by another transaction. This property is known as Durability.
Because of these three properties, a transaction must preserve database consistency, and this property is known as Consistency.
Whenever you need to use transactions! Relational databases are very good and are being used for many years, use it if it is more suitable for your application.
It is important for a beginner developer to know the various possibilities available and to build excellent applications!
To know more
Book: An Introduction to Database Systems (C.J. Date )
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