Tumalucious

Database...

Database is a structured set of data held in a computer. The data are typically organized to model relevant aspects of reality in a way that supports processes requiring this information. Database software enables you to organize and store data so that specific items of information can be retrieved easily and quickly in a structured fashion. Traditional databases are organized by fields, records, and files.

 A field is a single piece of information; a record is one complete set of fields; and a file is a collection of records.

Each record has a key field (primary field) which uniquely identifies a record. Using a key field can speed up operations such as searching and sorting. A key field also allows tables to be linked. Linking tables enables a database to create queries that retrieve data from several tables.

 A flat-file database has only one table, whereas a relational database has several linked tables.

An index is a table that contains two columns: one column stores a sorted list of the values in the field or fields being indexed and the second stores a pointer, which gives the location of each record in the table.

Indexes can speed up operations such as queries. Each field is automatically assigned default field properties depending on the data type. The field properties, which can be changed, determine how a field is stored, how it works and how it is displayed.

 An alternative concept in database design is known as Hypertext. In a Hypertext database, any object, whether it be a piece of text, a picture, or a film, can be linked to any other object. To access information from a database, you need a database management system (DBMS). This is a collection of programs that enables you to enter, organize, and select data in a database.

   *Advantages

-Reduced data redundancy

-Reduced updating errors and increased consistency

-Improved data access to users through use of host and query languages

-Improved data security

-Reduced data entry, storage, and retrieval costs

-Facilitated development of new applications program

   *Disadvantages

-Database systems are complex, difficult, and time-consuming to design

-Substantial hardware and software start-up costs

-Damage to database affects virtually all applications programs

-Initial training required for all programmers and user