Databases

Databases

1. A persistent and organised store of data.

2. Paper-based

   • Disadavantages
     • They can be destroyed easily,unlike a computer database
     • Not environmentally friendly - uses trees
     • If an adaption is needed to be made ,the whole database would need to be rewrote/reprinted
   • Examples
     • Menus
     • Yellow Pages
   • Advantages
     • It is cost effective initially
     • All age groups can use them

3. Computer-based

   • Advantages
     • Multiple people can access the database.
     • Computer databases are easier to make adaptions to because you would only have to change one field
   • When using the filter tool,the database hides the records that are not needed and only shows the records that are relevant to the filter used.
   • When you search in a certain field,it shows all the records but picks out the one you have searched for.
   • Examples
     • Search Engine
     • Criminal Records
     • School Registers
   • Boolean Operators can be used to refine filters and queries
     • The AND operator can be used to make sure that there is more than one field required to fit the criteria
     • The OR operator can be used to widen your search range.This can also be used to search for two different criterias at the same time
   • Relational Operators can be used in a query if you want a group of data that is either Less than an amount ( <), Equal to (=) or More than an amount (>)
   • There are four types of data types that can be entered into a database
     • Integer
       • This is a whole number
     • Real
       • This is a decimal number
     • Boolean
       • This is answer from a true or false question (e.g Yes or No)
     • String
       • Any combination of keys on the keyboard.
   • When doing a query,you need to enter the criteria you require to find a certain record

4. Both

   • Calendar
   • Homework Planner

5. Validation Checks

   • Presence Check
   • Type Check
   • Field Length Check
   • Range Check
   • Format Check
   • List Check