Database

Database

1. Validation checks

   • Type checks
     • Most basic.
     • Restricts input to the data type set. Such as Boolean, String, Integer.
     • e.g Entering numbers in phone number
   • Range checks
     • Limit the range of data the user can input.
     • e.g Day MUST be in between 1 to 31. Exam grades must be in between 'A' to 'G'
   • Check digits
     • Used with numbers.
     • Checks amount of numbers in a set of number
     • e.g ISBN book numbers which checks the books unique number to see if that book is that book
   • Presence check
   • Length checks
   • Lookup
   • Input masks
     • Turns the data to whatever the programmer wanted it to look like.
     • e.g Postcodes, product codes, National Insurance numbers

2. Data Types

   • String
     • Text
   • Integer
     • Number
   • Real
     • Decimal number
   • Boolean
     • Yes/no

3. Flat file Vs relation

4. Primary and foreign keys

   • Primary key
     • Its own key
     • Has to be unique
   • Foreign key
     • Used to connect two entities together
     • Not unique

5. Keywords

   • Entity
     • Also known as a table
     • A real world object
   • Attributes
     • Also known as a field

6. DBMS

   • Database Management System
   • Run reports
   • Manage records in a system
   • Run queries
   • User interface
   • Benefits
     • Easier to maintain
     • Set up by experts
     • Safe from coruption
   • Validation checks
   • Multiple people can access
   • Many access points
   • No disruption if one application updates