Databases - introduction to Microsoft Access

Key points:

  • Databases are made up of one or more tables
  • Each table contains data organised into records and fields
  • Records are the rows of the table, representing individual objects that the database is 'about' - for example, cars or people.
  • Fields are the columns of the table, representing properties - for example, date of birth, height, colour
  • Each record needs a special field, a key field, to act as identifier for the record.  This field must be completed (it can be done automatically) and each entry must be unique.

Before we create a database we need to think carefully about what the records should be and what fields of data we need.
Key points:

Every field is associated with a type.  These types determine what kind of information can be placed in the field and what can be done with it.  Typical fields include:

  • Text
  • Number
  • Date/Time
  • Boolean

Information entered into a database is subject to two kinds of checks:
  • Validation:  Checks that the data could be correct - has the right format, is in the right range, looks sensible.
  • Validation:  Checks that the data actually is correct by comparing it to something else, for example the original documents