Saturday, 7 December 2013

The Database Life Cycle



Before getting into the development of any system, you need to have strong a life-cycle model to follow. The model must have all the phases defined in the proper sequence, which will help the development team build the system with fewer problems and full functionality as expected.
The database life cycle consists of the following stages, from the basic steps involved in designing a global schema of the database to database implementation and maintenance:
•  Requirements analysis: Requirements need to be determined before you can begin design and implementation. The requirements can be gathered by interviewing
both the producer and the user of the data; this process helps in creating a formal requirement specification.
•  Logical design: After requirements gathering, data and relationships need to be
defined using a conceptual data modeling technique such as an entityrelationship (ER) diagram. This diagram shows how one object will connect to the other one and by what relationship (one-one or one-many). Relationships are.
•  Physical design: Once the logical design is in place,the next step is to produce the
physical structure for the database. The physical design phase involves creating
tables and selecting indexes.but an index is basically like an index of a book, which allows you to jump to a
particular page based on the topic of your choice and helps you avoid shuffling all
the pages of the book to reach the page of interest. Database indexes do
something similar; they manage and maintain the order of rows when inserted
into the table, which helps SQL queries pull data fast based on a provided value for
the index column.
Database implementation: Once the design is completed, the database can be
created through the implementation of formal schema using the data definition
language (DDL) of the RDBMS. The DDL consists of the statements that play key
roles in creating, modifying, and deleting the database or database objects. CREATE,
ALTER, and DROP are prime examples of a DDL.
Data modification: A data modification language (DML) can be used to query and
update the database as well as set up indexes and establish constraints such as referential integrity. A DML consists of the statements that play key roles in inserting,
updating and deleting the data from database tables. INSERT, UPDATE, and DELETE
are prime examples of a DDL.
•  Database monitoring: As the database begins operation, monitoring indicates
whether performance requirements are being met; if they are not, modifications
should be made to improve database performance. Thus, the database life cycle
continues with monitoring, redesign, and modification. 
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