Podcast
Questions and Answers
What does a primary key in a database ensure?
What does a primary key in a database ensure?
- Values cannot change
- Values must be unique (correct)
- Values can be empty
- Values may repeat across records
A foreign key can establish relationships between tables and may contain NULL values.
A foreign key can establish relationships between tables and may contain NULL values.
True (A)
What is an instance in the context of a database?
What is an instance in the context of a database?
A snapshot of the database at a given time.
A schema describes the overall ______ of the database.
A schema describes the overall ______ of the database.
Match the following types of schema with their descriptions:
Match the following types of schema with their descriptions:
Which of the following characteristics does not apply to primary keys?
Which of the following characteristics does not apply to primary keys?
CRUD operations can modify the instances of a database.
CRUD operations can modify the instances of a database.
List one key characteristic of a foreign key.
List one key characteristic of a foreign key.
What is the main purpose of a Database Management System (DBMS)?
What is the main purpose of a Database Management System (DBMS)?
In 1-Tier Architecture, the client and database are located on different machines.
In 1-Tier Architecture, the client and database are located on different machines.
What are the two types of database models mentioned?
What are the two types of database models mentioned?
APIs such as _____ and _____ are used for client-server communication in 2-Tier Architecture.
APIs such as _____ and _____ are used for client-server communication in 2-Tier Architecture.
Which architecture uses a direct database connection by the client application?
Which architecture uses a direct database connection by the client application?
DBMS allows users to retrieve and manipulate data through queries.
DBMS allows users to retrieve and manipulate data through queries.
Match the following types of DBMS architecture with their descriptions:
Match the following types of DBMS architecture with their descriptions:
What is a transaction in the context of a DBMS?
What is a transaction in the context of a DBMS?
Which of the following is NOT a characteristic of a candidate key?
Which of the following is NOT a characteristic of a candidate key?
A candidate key can contain NULL values.
A candidate key can contain NULL values.
What are the two categories of database schema?
What are the two categories of database schema?
The __________ table is linked to both the candidates table and the voters table through the IDNUMBER column.
The __________ table is linked to both the candidates table and the voters table through the IDNUMBER column.
Match the following types of database schema with their descriptions:
Match the following types of database schema with their descriptions:
What does the logical database schema define?
What does the logical database schema define?
The candidatesarchive table is used to store current data about candidates.
The candidatesarchive table is used to store current data about candidates.
What is the purpose of a database schema?
What is the purpose of a database schema?
What type of architecture includes an intermediate layer between the client and the server?
What type of architecture includes an intermediate layer between the client and the server?
In the hierarchical data model, a node can have multiple parents.
In the hierarchical data model, a node can have multiple parents.
Who developed the relational data model and in what year?
Who developed the relational data model and in what year?
The topmost node in a hierarchical data model is called the ______.
The topmost node in a hierarchical data model is called the ______.
Match the following data models with their characteristics:
Match the following data models with their characteristics:
Which data model was developed in 1968 and is considered the oldest?
Which data model was developed in 1968 and is considered the oldest?
The network data model organizes data in a tree structure.
The network data model organizes data in a tree structure.
What is one key feature of the relational data model in terms of data presentation?
What is one key feature of the relational data model in terms of data presentation?
Study Notes
DATABASE MANAGEMENT SYSTEM (DBMS)
- A DBMS is software that assists in creating and maintaining databases.
- It allows users to define, manipulate, and share data effectively across various applications.
HOW DBMS WORKS
- Application programs interact with the database by sending queries to the DBMS.
- Queries trigger transactions that may read data from or write data into the database.
DATABASE
- Databases are designed to store critical information, allowing quick and secure data access.
DBMS ARCHITECTURE
- Database architecture is chosen based on factors like database size, number of users, and user relationships.
TYPES OF DBMS ARCHITECTURE
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1-Tier Architecture:
- Users access the database directly on the same machine where the DBMS operates.
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2-Tier Architecture:
- Utilizes a client-server model where the client application communicates directly with the database server.
- APIs like ODBC and JDBC facilitate this interaction.
- Offers easier maintenance but can underperform with high user loads.
-
3-Tier Architecture:
- Includes an intermediary application server between the client and the database server.
- The client communicates with the application server, which processes queries and data management.
DATA MODELS
-
Hierarchical Data Model:
- Introduced by IBM in 1968, organized in a tree-like structure with a single parent per node.
-
Network Data Model:
- An advanced model using directed graphs allowing child nodes to have multiple parents, utilizing records and sets.
-
Relational Data Model:
- Developed by E.F. Codd in 1970, represents data in tables without physical links, emphasizing ease of query handling.
SCHEMAS AND INSTANCES
-
Instances:
- Represent the current state of the database, which can be altered by CRUD operations, but queries do not change instances.
-
Schema:
- Overall description of database structure, defining how data is stored.
-
Types of Schema:
- Logical Schema: Designs at a logical level.
- Physical Schema: Designs at the physical storage level.
- View Schema: Defines the design at the user view level.
KEYS IN DATABASE
-
Primary Key:
- Unique identifier for a table record, must be unique and not null.
-
Foreign Key:
- Column in one table that creates a link to the primary key in another table, maintaining referential integrity.
-
Candidate Key:
- A column or set of columns that can uniquely identify a record, must be unique and non-null.
DATABASE SCHEMA CATEGORIES
-
Physical Database Schema:
- Explains data storage methods, detailing structures like files and indices.
-
Logical Database Schema:
- Outlines logical constraints for the data, providing definitions for tables and integrity rules.
RELATIONSHIPS
- Relationships between tables ensure data integrity and connectivity. For example, the ballots table relates to the candidates and voters tables via IDNUMBER.
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Description
This quiz reviews key concepts of Database Management Systems (DBMS), including their functions and operations. It covers the essential elements that enable users to create, manipulate, and maintain databases. Test your understanding of how DBMS works and its significance in data management.
