Very early computer-based data processing was first available, there were no databases.
Data files are application program dependent e.g., data are by product of program.
As business applications became more complex, traditional file processing systems had limitations.
FLAT FILE
Early days of computing, every application stored its data into its own dedicated files.
It create unnecessary redundancies, resulting inconsistencies of data
WEAKNESSES OF FLAT FILE
Storage waste
Strong coupling between applications and data
Changes in a data file necessitates changes in all applications
Hard to manage simultaneous access by different users or applications to the same data without conflicts
Difficult to integrate applications
Lengthy development times
Excessive program maintenance
- 1970s: Hierarchical and Network database management systems
- Regarded as first-generation DBMS
- Still suffered: limited data independence and lengthy development times for application development
HIERARCHICAL DATABASE
One of the limitations of flat file is inefficient searching because of file type; e.g. serial file organization.
Hierarchical data models address searching by organizing data in a hierarchy of parent-child relationships.
LIMITATIONS OF HIERARCHICAL DBMS
Work well for one parent to one or more children, e.g. one customer to one or more loans
Multiple parents not work well; e.g. Two customers with one loan
Create duplicate information about the loan under both customers
Makes inefficient use of storage space to duplicate data
Lead to inconsistent data
Potential for errors when aggregating data; e.g. to find the total value of all outstanding loans
NETWOTK DATA MANAGEMENT
Not restricted to having one parent record
Two essential components: a schema and the database itself
Allow for multiple parents, such as two customers on a loan
Allow known as a many-to-many relation
Graphs that have directed edges and no cycles are known as directed acyclic graphs
LIMITATION OF NETWORK DBMS
Difficult to design, update and maintain
After a network database is deployed, if a database designer determines another entity or node type is needed, then programs that access the network database will have to be updated