Advantages

Reduction of data redundancy, which not only reduces the required disk storage space, but also speeds processing.Flexibility. If data changes, you can update the value in only one place. All queries, forms, and reports look in that place for the current values.Simplicity. The flat-file model used as the basis for a relational system dictates a simple, non-redundant method of data storage. Each table in the relational design is a single object containing data relevant to a particular aspect of the database, such as an employee, a product, or an order.Power. Storing the data in separate related tables allows grouping, searching, and retrieving the information in almost unlimited ways.Ease of management. With smaller, less-complicated tables, the information is much easier to locate and manage.

8. MS Access -is a relational database.

Tables are the fundamental objects at the heart of a relational database. They form the active basis for the information storage and retrieval system.

Once the information is arranged in separate tables, you can view, add, edit and delete information with online forms, search for and retrieve some of or all the information with queries; and print information as customized reports.

In Access the term database is more precisely used to define the collection of objects that store, track, manipulate, and retrieve data.

Differences between Access и Excel in storing data 1. Working with Excel you enter any information in a cell such as a text, a table a figure. So, in one column there may be data of different types – numbers, texts, dates, if necessary. Access table differs from Excel spreadsheet: you can’t have data of different types in one column. 2. Access allows not only enter data in tables but also control them by setting specific rules at the table level. So, it won’t let you save data that don’t meet required rules.

3. Excel is convenient to work with if a table contains a limited number of rows. Database tables may contain a huge number of records. Database management system offers effective tools to retrieve necessary information. 4. If you store all necessary information in Word documents and Excel spreadsheets, then while accumulating it you can meet the problem of dealing with a great number of files. Access allows you to store all data in one file and have access to the page by page, that is not exceeding limitations on computer resources.

5. Access allows to relate tables and, therefore, use data from different tables. For users it will be the same as working with one table. Implementing this mode in Excel is very complicated, sometimes impossible. 6. Setting relations with different tables Access allows to avoid duplicate data, save computer memory and increase speed and accuracy of processing.

9. Types of Relationships

Tables can be related in three different ways:

• one-to-one,

• one-to-many, and

• many-to-many.

The type you define depends on how many records in each table are likely to have the same value.To relate tables, one of them must include a field that contains a unique value in every record. This can be a primary key field or a field with a unique index that allows no duplicate values. A primary key or a unique index can also be a combination of two or more fields whose combined value is unique for all records.

For example, the Employee ID can be a unique number that identifies an employee. If you want to use names in a key or index, you’d probably need to include both the first and last names to ensure unique values.

10. Referential Integrity

Referential integrity is an optional system of rules that guarantees the relationships are valid and the database will remain intact as data is entered, edited, or deleted.

The basic rule of referential integrity is this: