Files and Relational Databases
Files and Relational Databases
What is a file?
• contains groups of records used to provide information for operations, planning, management and decision making.
• can be used for storing data for an indefinite period of time, or they can be used to store data temporarily for a specific purpose.
FILE TYPES
• Master Files -- contain records for a group of entities. The attributes may be updated often, but the records themselves are relatively permanent. These files tend to have large records containing all the information about a data entity. Examples : patient records, customer records, a personnel file, and a parts inventory file.
• Table Files -- contains data used to calculate more data or performance measures.
Examples : tax table and table of postage rates.
• Transaction Files -- used to enter changes that update the master file and produce reports. Examples : order record, payment record, purchase record, etc.
• Record Files -- very useful because users can take files to other computer systems and output to specialty devices. Examples : Employee Record, Medical Record, Criminal Record, Pupil Record
DATABASES
• A database is intended to be shared by many users.
• There are three structures for storing database files:
❑ Hierarchical database structures
❑ Network database structures
❑ Relational database structures
Hierarchical database structures
A kind of database management system that links records together like a family tree such that each record type has only one owner.
For example, an organization might store information about an employee, such as name, employee number, department, salary. The organization
What is a file?
• contains groups of records used to provide information for operations, planning, management and decision making.
• can be used for storing data for an indefinite period of time, or they can be used to store data temporarily for a specific purpose.
FILE TYPES
• Master Files -- contain records for a group of entities. The attributes may be updated often, but the records themselves are relatively permanent. These files tend to have large records containing all the information about a data entity. Examples : patient records, customer records, a personnel file, and a parts inventory file.
• Table Files -- contains data used to calculate more data or performance measures.
Examples : tax table and table of postage rates.
• Transaction Files -- used to enter changes that update the master file and produce reports. Examples : order record, payment record, purchase record, etc.
• Record Files -- very useful because users can take files to other computer systems and output to specialty devices. Examples : Employee Record, Medical Record, Criminal Record, Pupil Record
DATABASES
• A database is intended to be shared by many users.
• There are three structures for storing database files:
❑ Hierarchical database structures
❑ Network database structures
❑ Relational database structures
Hierarchical database structures
A kind of database management system that links records together like a family tree such that each record type has only one owner.
For example, an organization might store information about an employee, such as name, employee number, department, salary. The organization