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Transcript
Relational Database Management System (RDBMS) – MS Access Database Management System (DBMS) A set of programs that permits an organisation to: Using a DBMS, users can create new database files add, delete, alter, and sort data make enquiries and print reports The DBMS will centralise data create database files manage them efficiently access the data when required allow many users to simultaneously access the central database restrict access for each user to those parts of the database that they are entitled to view or change MS Access has many of the features of a DBMS. Basic Components Tables Forms Queries Reports Tables A table for each separate entity Design mode allows user to define a data structure for the table A primary key – which must be a unique identifier for each record - must be defined. (Access does provide an Autonumber function is there is no natural unique identifier. Forms A user-friendly method of entering data for the main user(s) of a database Usually has one data source, which may be a table or a query The objects that allow fields to displayed and/or modified are known as controls Design is very important Order of controls Layout of controls Queries Used to create subsets of data held in tables Used to combine the contents of more than one table This is achieved via the relational links that are created between tables The are several types of query Simple select query Update query Append query Delete query Crosstab query Reports Reports are usually used in conjunction with queries to produce sorted output satisfying particular criteria MS Access provides powerful wizards to produce reports with various sort, grouping and style options. Relationships The relational database model depends upon the creation of relational links between separate entities (tables) One-to-Many relationship For example in a surgery database, a doctor would have many patients Doctors Patients One-to-one relationship – a doctor would have one expense account Doctors Expenses