Intro to Databases - DBMS Exam #1

File Processing System

File User > User-Processing Application > User File

What are the problems with File Processing Systems

1) Data is separated & isolated

2) Data is often duplicated

3) Incompatible data files

4) Program- Data dependence

What is Program-Data Dependence?

When changes in data definition require changing the programs that access that data

How are Databases Centralized?

user 1, user 2…user n > DBMS > Database

A Database is a centralized & integrated source of an organization’s data

What is a Database?

An integrated collection of logically related data elements. A database consolidates records previously stored in separate files.

What is the Data Hierarchy?

1) Database (a set of related files)

2) File (a collection of related records)

3) Record (a group of logically related fields)

4) Field (an attribute)

5) Character (single alphabet, number, or other symbol)

What are other names for a Table?

File or Relation

What are other names for a Row?

Record or Tuple

What are other names for a Column?

Field or Attribute

What are the components of a Database

What are the Types of Data?

1) Users’ data

2) Metadata

3) Indexes

4) Application Metadata

What is User Data?

1) A user data table is called a “relation”

2) its columns are called “attributes”

3) its rows are "specified instances”

4) Its relations must be structured properly

What is Metadata/a Data Dictionary?

A description of the structure of the database, which is stored in system tables

What are some examples of Metadata

1) Table names

2) Field names

3) Data types

4) Primary key fields

5) Data constraints

6) Relationships between tables

What is an Index?

An ordered arrangement of keys and pointers that are created on fields or combination of fields, which is frequently accessed.

What are the Pros & Cons to Indexes?

Pros:

1) Quicker access to data

2) Let’s you sort data more easily

Cons:

1) Requires overhead processing (everytime a row is updated/deleted, the index must also be updated)