Page 108 - DCAP516_COMPUTER_SECURITY

Computer Security

Notes Storing the data itself into persistent storage.
Manipulation of the database.
Querying the database to retrieve desired data.

Updating the content of the database.
Databases can be analyzed at different levels:
Conceptual Modeling
Logical Modeling

Physical Modeling
8.22 Keywords

Data Dictionary: Dictionary that stores information about the structure of the database. It is
used heavily. Great emphasis should be placed on developing a good design and efficient
implementation of the dictionary.
Data Files: File that store the database itself.
Database Manager: The interface between low-level data and application programs and queries.

DDL Compiler Converts: A compiler the DDL statements to a set of tables containing metadata
stored in a data dictionary.
DML pre-compiler: Converts DML statements embedded in an application program to normal
procedure calls in a host language. The pre-compiler interacts with the query processor.
Entity: An entity in a payroll system is an individual employee.
Field/Item: A field or item of data is one or more bytes that contain data about an attribute of an
entity in the information system.
File: A file is a collection of related records.
File Manager: Manages allocation of disk space and data structures used to represent information
on disk.
Indices: Provide fast access to data items holding particular values.
Query Processor: Translates statements in a query language into low-level instructions the
database manager understands (May also attempt to find an equivalent but more efficient form).
Record: A record is a collection of fields relating to a specific entity.
Relationships: A relationship is a connection between entities.

Sequential Access: With a sequential access file, records must be read in the same order as they
were written to the storage media.

8.23 Review Questions

1. What is data? Explain the hierarchy of data and how the data can be found in a file.

2. Why is a computer known as a data processor? Give Reasons.
3. Discuss data processing and its concepts.
4. What are the different types of data processing and number processing? Explain.

102 LOVELY PROFESSIONAL UNIVERSITY