Understanding Databases: Relational Models and Access

What is a Database?

A database is a structured data support system that allows us to store and process data quickly, safely, and efficiently.

A database consists of fields, records, and files. We define:

• Field: Each of the elements that make up a record, such as name, address, town, and telephone.
• Record: A set of interrelated fields, such as personal data belonging to a shareholder of a video store.
• File: Consists of the union of multiple records.

What is a Relational Database?

Using relational databases is useful when multiple records of a database are related to the same record in another database. A simple and intuitive way of structuring data is using tables, i.e., arranged in rows and columns. The relational model uses the table structure for organizing data. In relational terminology:

• Each row is a record. A record stores all information on an item (product, employee...).
• Each column is a field. One field stores a category or type of information (product name, employee ID...).

For a table to be part of the relational model, it must meet the following conditions:

• The kind of record should be unique, i.e., all records must have the same fields.
• Each record must be unique; no two records can be equal.
• Each field must be identified by a specific name (name...).
• All values in a column must belong to the same category.

To identify a particular record in the relational model, a primary key is used.

A primary key is a field in the table that uniquely identifies a record. There cannot be two records with the same primary key. For example, a field containing names should not be used as a key, as there's probably some record of recurrence.

What is Access?

Microsoft Access is a management system for relational databases (RDBMS) that permits storing and retrieving information (according to the relationships that are established) in the tables of a database. With Access, you can perform the following tasks:

• Querying: The usefulness of queries is to be able to select all records from a database that meet certain conditions.
• Build forms for entry and exit: Forms are very useful when entering or displaying data for a particular record so that information pertaining to a record displays in a clear and concise manner.
• Build reports: A report is used to provide a printed sheet of data on a set of records.

Creating a Database

1. FILE -> New Database
2. Select the drive and folder where you want to save the database
3. Enter a name for the database in the "Filename" field
4. Click on Create.