Databases | Computer for GCSE/IGCSE - Year 11 PDF Download

Single Table Databases

• A database is a structured collection of data allowing for quick search, sorting, filtering, and analysis.
  • Data in a database can encompass various types such as text, images, videos, and sound.
• Databases utilize tables to house data.
• Tables contain records of data, each depicted in a single row.
  • Each row in a customer table represents the information stored about a single customer, known as the customer's record.
  • The table contains a total of 3 records, each comprising fields such as CustomerID, FirstName, LastName, Date of Birth (DOB), and Phone Number.
• Visual Representation of a Database Table Containing Customer Details:

• Fields are represented by the columns in a table:
  • The fields in a table correspond to the columns, with the customer table encompassing 5 fields.
  • The first row in the table serves as the header, displaying the names of the fields and guiding the data stored within them.
  • Each field in the table possesses a data type, dictating the kind of data that can be entered into that particular field.

Validation and Verification

• Verification checks ensure that entered data is correct and accurate, often involving a review process where data entered by one person is verified by another.
• When creating a table, validation rules can be set for different fields:
  • These rules dictate the type of data permissible in each field.
  • Various types of validation checks are applied to restrict the range of acceptable data for each field.

The different types of validation check

Data Types

• Table fields in a database are represented by columns.
• There are five fields in the customer table:
  • CustomerID
  • FirstName
  • LastName
  • DOB
  • PhoneNumber
• A Database Table Containing Customer Details:
  
• Each field in a table is associated with a data type.
• Common data types include:
  • Text/Alphanumeric
  • Character
  • Boolean
  • Integer
  • Real
  • Date/Time
• For instance, phone numbers are typically assigned the text/alphanumeric data type because they start with a 0. If you were to assign the data type Integer to a phone number, it would lead to the removal of the initial 0.

Database Data Types