Database system development life cycle

Database planning is the management activities that allow the stages of the database system development lifecycle to be realized as efficiently and effectively as possible.

System Definition involves identifying the scope and boundaries of the database system, including its major user views. A user view can represent a job role or business application area.

Requirements collection and analysis is the process of collecting and analyzing information about the organization that is to be supported by the database system, and using this information to identify the requirements for the new system.

Requirements collection and analysis is a preliminary stage to database design. The amount of data gathered depends on the nature of the problem and the policies of the organization. Identifying the required functionality for a database system is a critical activity, as systems with inadequate or incomplete functionality will annoy the users, and may lead to rejection or underutilization of the system. However, excessive functionality can also be problematic as it can overcomplicate a system, making it difficult to implement, maintain, use, and learn.

Database design is the process of creating a design that will support the organization’s mission statement and mission objectives for the required database system. This stage includes the logical and physical design of the database.



DBMS selection

The aim of DBMS selection is to select a system that meets the current and future requirements of the organization, balanced against costs that include the purchase of the DBMS product and any additional software/hardware, and the costs associated with changeover and training.

[caption id="attachment_636" align="aligncenter" width="204" caption="Database Design Life Cycle"][/caption]

Application design involves designing the user interface and the application programs that use and process the database. This stage involves two main activities: transaction design and user interface design.

• Transaction Design

An action, or series of actions, carried out by a single user or application program that accesses or changes the content of the database.

There are three main types of transactions:

• retrieval transactions


• update transactions


• mixed transactions

• User interface design

In addition to designing how the required functionality is to be achieved, we have to design an appropriate user interface for the database system. This interface should present the required information in a user-friendly way.

Prototyping involves building a working model of the database system, which allows the designers or users to visualize and evaluate the system.

There are two prototyping strategies in common use today:

• Requirements prototyping and


• Evolutionary prototyping.

Requirements prototyping uses a prototype to determine the requirements of a proposed database system and once the requirements are complete the prototype is discarded. While evolutionary prototyping is used for the same purposes, the important difference is that the prototype is not discarded but with further development becomes the working database system.

Implementation is the physical realization of the database and application designs.



Data conversion and loading involves transferring any existing data into the new database and converting any existing applications to run on the new database.

Testing is the process of running the database system with the intent of finding programming errors.

Operational maintenance is the process of monitoring and maintaining the system following installation.

The process of monitoring and maintaining the database system following installation.

In this stage, the database system now moves into a maintenance stage, which involves the following activities:

• Monitoring the performance of the database system. If the performance falls below an acceptable level, the database may need to be tuned or reorganized.

• Maintaining and upgrading the database system (when required). New requirements are incorporated into the database system through the preceding stages of the lifecycle.

For More detail please read the book Database Solutions A step-by-step guide to building databases

A Tutorial on Database Design concept please click here.

How to Delete All Objects for a User in Oracle

If you don't have system level access(Sys or System), and want to clean your schema, the following sql will produce a series of drop statments, which can then be executed.

select 'drop '||object_type||' '|| object_name||  DECODE(OBJECT_TYPE,'TABLE',' CASCADE CONSTRAINTS;',';')
from user_objects

Then, I normally purge the recycle bin to really clean things up. To be honest, I don't see a lot of use for oracle's recycle bin, and wish i could disable it... but anyway:

purge recyclebin;

Following Script can run the full System

SET feedback off
SET verify off
SET echo off
PROMPT Number of objects IN the schema:
SELECT COUNT(*) FROM user_objects;
PROMPT Finding objects TO DROP

SET termout OFF
SET pages 80
SET heading OFF
SET linesize 120

PURGE RECYCLEBIN;

SPOOL c:\cleanup_schema.sql
SELECT 'SPOOL c:\cleanup_schema.log' FROM dual;
SELECT 'DROP '||object_type||' '|| object_name||  DECODE(object_type,'TABLE',' CASCADE CONSTRAINTS;',';') FROM user_objects ORDER BY object_id DESC;
SELECT 'PURGE RECYCLEBIN;' FROM dual;
SELECT 'PROMPT After cleanup, number of objects remaining in schema' FROM dual;
SELECT 'SELECT COUNT(*) FROM user_objects;' FROM dual;
SELECT 'SPOOL OFF' FROM dual;
SELECT 'EXIT;' FROM dual;

SPOOL OFF

SET termout ON
PROMPT Dropping Objects now ...
-- Execute the sql file created earlier
--@c:\cleanup_schema.sql
EXIT
/

Reff: http://forums.oracle.com/forums/message.jspa?messageID=1057359