Chapter 10:- Managing a database
-The database is a collection of data organized in a manner that allows accessing retrieval and use of that data.
-Data is a collection of unprocessed items such as text, number, images, video, and audio.
-Information is where it processed data such as documents. images, video, and audio.
-Database software,often called a database management system (DBMS), allows users to create a computerized database, create forms and reports from the data, sort and retrieve data and modify and delete data.
-Data integrity identifies the quality of the data. Garbage in, garbage out (GIGO) points out the accuracy of a computer's output depends on the accuracy of the input .
Valuable information should have the following characteristics:-
- Accurate- very valuable information need to be accurate and out of error
- Verifiable-
- Timely- information need to be on time
- Organized-
- Accessible
- Useful
- Cost-effective
The Hierarchy Of Data: -
- Character
- Field
- Records
- Files
-File maintenance refers to the procedures that keep data current. an example of file maintenance is adding records, modifying records, and deleting records.
-Adding record is add new records to a file when they obtain new data.
-Modifying records is where users modify a record to correct inaccurate data or update old data.
-Deleting records is where the users delete the old record when no longer needed.
Validation: -
Validation compares data with a set of rules or values to find out if the data is correct. Database validation is required when database get corrupted to check for corruption.
Type of validity checks: -
- Alphabetic/Numeric check
- Range check
- Consistency check
- Completeness check
- Check digit
File processing versus Database approach:-
File processing system:
- Each department has its own set of files.
- Have data redundancy.
- Isolate data.
Database approach:
- Programs and users share data.
- Reduce data redundancy.
- Improve data integrity.
- Share data.
- Allow easier access.
- Reduce development time.
- More vulnerable.
Database Management Systems: -
- Data dictionary- contains data about each file in the database and each field in those lines.
- Query language- consist of simple, English-like statements that allow users to specify the data to display, print or store.
- Query by example (QBE)- provide a graphical user interface to assist users with retrieving data.
- Form- window on the screen that provides areas for entering or modifying data in a database.
- Report generator- allows users to design a report on the screen, retrieve data into the report design and then display or print the report.
- Security- only authorized users can access data at permitted times such as access privileges and the principle of least privilege.
- Backup and restore- to save the data in the database in another storage medium and can be returned to its original form later.
- Data model- consists of rules and standards that define how the database organizes data.
For example:
- Relational database- stores data in tables that consist rows and columns. The relationship is the link within the data.
- Object-oriented database (OODB)- stores data in objects. Examples of applications are a multimedia database, groupware database, computer-aided design database and hypertext database.
- Object-relational database- create relationship between object-oriented data.
- Multidimensional database- can store data in more than two dimensions of data. A.k.a hypercube and it can consolidate data much faster than a relational database.
- Data warehouse- a huge database that stores and manages data required to analyze historical and current transactions.
Features of Web database: -
- Shop for products or services- Amazon, Ebay, Alibaba
- Buy or sell stocks- NASDAQ, Suretrader.com.
- Search for a job- Jobstreet, Moster.com
- Make airline reservations- Air Asia, Malaysia Airline, Royal Brunei Airline.
- Register for college classes- UCSI Information Integrated System (IIS).
- Check semester grades- UCSI IIS, LMS.
Database Administration:-
The database design guidelines
- Determine the purpose of the database.
- Design the table or files.
- Design the record and fields for each table or files.
- Determine the relationships among the table and files.
Database analysts and administrators are responsible for managing and coordinating all the database activities.
- Database analyst (DA)- decides on proper field placement, defines data relationships, and identifies users access privileges.
- Database Administrator (DBA)- Creates and maintains the data dictionary, manages security, monitors performance, and checks backup and recovery procedures.
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