INFORMATION TECHNOLOGY DATABASE MANAGEMENT

A database is a collection of information organized to provide efficient retrieval. The collected information could be in any number of formats (electronic, printed, graphic, audio, statistical, combinations). There are physical (paper/print) and electronic databases. WHAT IS A DATABASE?

Database management is the process by which data is stored on a computer of other means so that there is efficient retrieval, updating and manipulation of data. DATABASE MANAGEMENT

A database package is a programme that is used to create and manage a computerised database. DATABASE PACKAGE

A manual database is one in which the data is stored physically. Example a filing cabinet. Each draw may store different type of data relating to the same subject. Manual and computerised database.

In a computerised database the data is stored electronically and can be managed more efficiently and effectively. Manual and computerised database.

Read chapter 14 LOG ON TO IT. List five (5) advantages and five disadvantages of a computerised database. ASSIGNMENT

Relational database A relational database is one that stores data in tables that consist of rows and columns. Each column has a unique name and each row has a primary key. DATABASE TERMINOLOGIES

Structure of a relational database DATABASE TERMINOLOGIES Database FileTableFieldCharacterRecord

Table A table is a set of data elements (values) that is organized using a model of vertical columns (which are identified by their name) and horizontal rows. A table has a specified number of columns, but can have any number of rows.... DATABASE TERMINOLOGIES

Table A table may also be referred to as a relation A table consist of rows also referred to as (record or tuple) and, Columns also referred to as (attribute or fields) DATABASE TERMINOLOGIES

Entity An entity is a person, place, thing or event for which data is collected and maintained. for example... A library system may contain data about different entities like BOOK and MEMBER. The entity may also be referred to as the subject DATABASE TERMINOLOGIES

Primary key – Field in a database table that uniquely identifies each record. The primary key cannot be null or duplicated. It is used mainly for accessing or searching a database since it will only return one record. DATABASE TERMINOLOGIES

Secondary key – An attribute (field) designed as an alternate means of accessing data; this attribute is not necessarily unique, or non-null. A search using a secondary key may return more than one record. DATABASE TERMINOLOGIES

Composite key – A primary index in a table that consists of more than one field so that no two records within the table can have the same combination of values in these fields. An example would be a table of contacts where the composite key combined the name and phone number fields.... DATABASE TERMINOLOGIES

Alternate key – any key which is not selected to be the primary key. Another name for the secondary key. DATABASE TERMINOLOGIES

Foreign Key– A column (field) in a database table that is used to match records with data in another table. One example would be a Customer ID field which is used as the primary key in the main Customer table and then as a foreign key in a table which lists the customer orders.. The first table is referred to as the referencing table and the second table is referred to as the referenced table. DATABASE TERMINOLOGIES