Databases

Databases

1. Databases are in a table

   • The records are grouped in a table
     • Each field is in a record

2. Storing data in a database brings advantages

   • Data can be accessed speedily and manipulated to form new data
   • Databases can be shared
   • Data validation can take place, the database can be set up to accept only stock numbers of the format 'one letter, then five numbers'

3. DMBS stands for database management system

   • An ability to check data inconsistencies
   • An ability to minimise duplicated data
   • An ability to allow multiple users to access the data at the same time
   • An ability to obtain related data from different tables in a file system by linking them one to another
   • The provision of a customisable user interface to make the data understandable
   • The capability to keep the data secure

4. Tables represent an entity

5. A table has a primary key

   • Primary keys can tell 2 names for example apart

6. Some tables have a foreign key

   • Foreign keys link 2 tables togheter

7. A form is a user-friendly to enter data into a table

8. A query is a way of interrogating a database to find out specific information

9. Modules is a piece of program code that manipulates data in some specific way

10. Report is an output of a database, that displays the result of a query

11. Validation

    • Range check, numerical data has to be between one number and another
    • Presence check, checking the user has entered something
    • Type check, not allowing letters into a fields
    • Lookup, provides the user with a drop down list
    • Length check, whatever is entered into a field has to be a certain numbers of characters long
    • Format check, some pieces of data are formed of characters in specific orders