Database

Database

1. Flats file Vs relational

2. Keywords

3. Validation checks

   • A validation check is a rule that is built into a database that the data entered is:
     • Sensible
       • Reasonable
         • Within acceptable boundaries
           • Complete
   • Type Checks
     • If a user tries to enter text in a data field or alphabetic characters in a numeric field, their entry will be rejected.
       • Examples: Numeric, Boolean, Date/Time and Image
   • Range checks
     • These are used to limit the range of data a user can enter.
       • Examples: Exam grades, Gender, Number game(1,10) you would enter 0,11
   • Check digits
     • This type of check is used with numbers. An extra 'check digit' is calculated from the numbers to be entered and added to the the end.
       • Examples: 10 Digits ISBN number which uniquely identifies books. The last number of the ISBN is actually the check digit for the other number
         • The ISBN 0192761501
   • Presence checks
     • These simply check that an entry has been made in a particular field i.e. a null value(empty field) is not permitted.
       • Examples: An application for a passport must have the applicant's surname, survey, forms
   • Length Checks
     • All alphanumeric data has a length. A single character has a length of 1 and a string of texts such as "Hello World" has a length of 11( spaces are counted in text strings)
       • Examples: Moblie phone number are stored as text and should be 11 characters in length.
   • Lookup
     • A lookup check takes the value entered and compares it against a list of values in a separate table.
       • Examples: Male or female drop-down lists
   • Input Masks
     • Certain alphanumeric fields in a database may require entry in a particular format e.g. a mixture of numbers and letters
       • Examples: Postcodes, National Insurance, driving licence numbers or product codes.

4. Primary & foreign keys

5. Data Types

6. DBMS

   • Database management system
   • Manage records in tables
   • Run queries
     • >< And or Not
   • Run reports
   • User interface
   • Benefits
     • Easier to maintain/ secure
     • Database is safe from corrupt
     • Set up by experts for use of the user
     • Can be access in multiple ways, such as tablets, Iphones, android, windows.
   • Validation