Relational Database

Relational Database

1. Tables

   • The products field data is linked to a product table using a combo box. The code is entered by a lookup wizard. Field names are shown in columns and records are shown in rows. The customer ID field in the customer table can be set up as a primary key
   • The table can be modified directly. Using standard functions for insert/delete record. Modifying the field content- more user friendly ro use data entry form

2. Reports are used to summarise and present data. A report is required for a specific issue. when a report is run it will include the current and up-to-date data form, the database outputs include: on screen viewing of a table, form or query. export of data to other applications, such as word processors and spread sheets, graphs and charts can be included in reports. Many people run reports to print them out, people view reports on screen or attach them to an email or even export them.

3. Queries can perform many different functions such as retrieving explicit data from one or more tables. Once the query has been saved it can be opened. Because criteria were entered into the query, the dialogue boxes will be produced automatically. Queries are normally designed to be used as the basis for report creation. Linking data tables can reduce the duplication of data, making it simpler to keep information up to date and increasing both the accuracy & the consistency of data. Customer details have to be entered more than once; this can lead to inconsistency for example varied spelling of the persons name.

4. Customers and sale tables are linked by Customer ID primary key. A primary key is a unique field that is used to link tables. Data entry forms can be based on: Main form with customer details, sub form with customer sales. Data entry forms can be used to: add records and input data, edit or modify data, delete records.

5. Specific features of a database: most database software has a range of wizards to help the user create a database, table consists of a series of field names and data types.

6. Flat file and relational databases: a database is simply a tool for collecting and organising information, it can be used to store information about customer, booking order or anything that is required by a business, small businesses store data in a spread sheet, however, as the list grows it can get difficult to manage.

7. In flat file databses: all data is contained in one table- it becomes difficult to manage when the list is long, flat file databases can be created in spreadsheets, word processors and all databases, each row of the table is known as a record

   • In relational databases: The data is stored in separate tables or entities, all the data tables are linked by key fields, Relational database management systems are used to control who has access to what.