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Questions and Answers
Which database structure is commonly used for analytical databases that support Online Analytical Processing (OLAP)?
Which database structure is commonly used for analytical databases that support Online Analytical Processing (OLAP)?
In a Hierarchical Structure, what type of relationships exist between records?
In a Hierarchical Structure, what type of relationships exist between records?
What is the primary purpose of the Join operation in Relational Structures?
What is the primary purpose of the Join operation in Relational Structures?
What is the term for combining data and operations in Object-Oriented Structures?
What is the term for combining data and operations in Object-Oriented Structures?
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In Relational Structures, what do rows and columns represent?
In Relational Structures, what do rows and columns represent?
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Which of the following is NOT a characteristic of Multidimensional Structures?
Which of the following is NOT a characteristic of Multidimensional Structures?
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What is the term for creating a new object by replicating some or all of the characteristics of a parent object in Object-Oriented Structures?
What is the term for creating a new object by replicating some or all of the characteristics of a parent object in Object-Oriented Structures?
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Which database structure is commonly used in some mainframe DBMS packages?
Which database structure is commonly used in some mainframe DBMS packages?
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What is the primary responsibility of a Database Administrator (DBA)?
What is the primary responsibility of a Database Administrator (DBA)?
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What type of information is stored in a data dictionary?
What type of information is stored in a data dictionary?
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What is the purpose of the data planning process in database development?
What is the purpose of the data planning process in database development?
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What is represented in an entity relationship diagram?
What is represented in an entity relationship diagram?
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What is the outcome of the database design process?
What is the outcome of the database design process?
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What is the purpose of logical design in database development?
What is the purpose of logical design in database development?
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What is the purpose of physical design in database development?
What is the purpose of physical design in database development?
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What is the relationship between a schema and a subschema?
What is the relationship between a schema and a subschema?
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Study Notes
Database Structures
- Common database structures include: Hierarchical, Network, Relational, Object-oriented, and Multi-dimensional
Hierarchical Structure
- Early DBMS structure
- Records arranged in a tree-like structure
- Relationships are one-to-many
Network Structure
- Used in some mainframe DBMS packages
- Many-to-many relationships are possible
Relational Structure
- Most widely used structure
- Data elements are stored in tables
- Row represents a record; column is a field
- Can relate data in one file with data in another, if both files share a common data element
- Relational Operations:
- Select: create a subset of records that meet a stated criterion
- Join: combine two or more tables temporarily
- Project: create a subset of columns in a table
Multidimensional Structure
- A multidimensional database is created from multiple relational databases
- Variation of relational model
- Uses multidimensional structures to organize data
- Data elements are viewed as being in cubes
- Popular for analytical databases that support Online Analytical Processing (OLAP)
Object-Oriented Structure
- An object consists of:
- Data values describing the attributes of an entity
- Operations that can be performed on the data
- Encapsulation: combine data and operations
- Inheritance: new objects can be created by replicating some or all of the characteristics of parent objects
- Used in object-oriented database management systems (OODBMS)
- Supports complex data types more efficiently than relational databases (e.g. graphic images, video clips, web pages)
Evaluation of Database Structures
- Hierarchical:
- Works for structured, routine transactions
- Can’t handle many-to-many relationships
- Network:
- More flexible than hierarchical
- Unable to handle ad hoc requests
- Relational:
- Easily responds to ad hoc requests
- Easier to work with and maintain
- Not as efficient/quick as hierarchical or network
Database DevelopmentRoles
- A Database Administrator (DBA) is in charge of enterprise database development, improving the integrity and security of organizational databases.
Database Development Tasks
- Uses Data Definition Language (DDL) to develop and specify data contents, relationships, and structure.
- Stores data specifications in a data dictionary or a metadata repository.
Data Dictionary
- A data dictionary contains data about data (metadata) and relies on specialized software to manage a database of data definitions.
- It contains information on:
- Names and descriptions of all types of data records and their interrelationships.
- End users’ access and use requirements for application programs.
- Database maintenance.
- Security.
Database Development Phases
Data Planning Process
- Develop an enterprise model that defines the basic business process of the enterprise.
- Define the information needs of end users in a business process.
- Identify key data elements needed to perform specific business activities using entity relationship diagrams.
Database Design Process
- Represent data relationships in a data model that supports a business process.
- This model becomes the schema or subschema for:
- The physical design of the database.
- The development of application programs to support business processes.
Logical Design
- A schema provides an overall logical view of relationships.
- A subschema provides a logical view for specific end users.
- Develop data models for DBMS.
Physical Design
- Determine how data will be physically stored and accessed on storage devices.
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Description
Quiz about common database structures, including hierarchical, network, relational, object-oriented, and multi-dimensional structures.
