Databases

Databases

1. A database is a large collection of data tables and links between them, structured in a way that data isn't repeated

2. Database data can be accessed by multiple users simultaneously running different tasks

3. A database management system is the programme which controls access to the data

4. Disadvantages of a Single Table Filing Systems (flat files)

   • Duplicated files is a waste of memory
   • Data may be updated on one record but not on another therefore data can be inconsistent
   • Multiple updates would be needed to change a single name
   • Data is not sharable

5. Relational Databases

   • Data is stored in more than one table
   • Tables are linked by their key fields
   • Most commercial databases are relational databases
   • relationships are formed by joining he primary keys in one table to secondary keys in another table.