Database
Shared collection of logically related data (and a description of this data), designed to meet the information needs of an organization.
What came before
File-based systems for handling data
A collection of programs that carry out tasks. Each program manages its own data. Data definition is embedded in the program. Data not shared between programs.
Disadvantages?
Duplication of data – time consuming to enter. Inconsistencies.
Isolation of data – harder to access management information.
Program-Data dependence – the data and program code are stored together (in the same file). It is more difficult to change the data structure or the program (a change to one could impact on the other).
The Database Approach:
Shared collection – can be used simultaneously by many departments and users.
Logically related - comprises the important objects and the relationships between these objects.
Description of the data – the system catalog (meta-data) provides description of data to enable data independence.
Database metadata:
Describes the data
Attribute name
Size
Type
Constraints on the data (validation)
Format
Creating the HotelChain data,...
the 4 tables done(Hotel, Room, Booking, and Guest),
14 questions in the worksheet all of them done except number (3).
I think I'll need help with it.
