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Questions and Answers
What do the rectangles in an ER Diagram represent?
What is the primary purpose of creating an ER Model?
Who proposed the concept of the ER Diagram?
What shapes are used to represent relationships in an ER Diagram?
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Why is ER modeling considered a best practice before implementing a database?
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What is a major disadvantage of using a single database in an organization?
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When should a DBMS not be used?
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What does the Database Architecture represent?
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Which DBMS architecture is known as the simplest form?
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What is a key benefit of the Two Tier Architecture?
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In a 2 Tier Architecture, where does the presentation layer reside?
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Which of the following is an example of a two tier architecture system?
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What is one of the limitations of a Database Management System as mentioned?
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What must be true about a key attribute referenced in a referential integrity constraint?
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Which operation is used to change the values of some attributes in existing tuples?
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What could happen if a tuple is deleted that is referenced by foreign keys?
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What is a requirement for each column in a relational database table?
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Why is the relational database model considered simpler than other models?
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Which statement is NOT a best practice when creating a relational model?
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What is referred to when discussing the structural independence of relational databases?
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Which is NOT a basic update operation in a relational database model?
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What is the primary purpose of the SQL SELECT statement?
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Which SQL command is primarily used to filter records based on specific conditions?
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In which part of an SQL SELECT statement do you specify the table from where to retrieve data?
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What must be included when retrieving data from multiple columns in an SQL SELECT statement?
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What is indicated by the ORDER BY clause in an SQL query?
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If you want to query the ages of expats from a specific home country using SQL, which element is essential in your SELECT statement?
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Which of the following commands is not categorized as an SQL query command?
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When writing a basic SELECT statement, what is the first part that must be specified?
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What advantage does the relational model provide regarding query capability?
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Which of the following is NOT a key component of the relational model?
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Which constraint is associated with the validity of attributes in the relational model?
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What is a common disadvantage of relational databases as they scale?
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What does the term 'scalability' refer to in the context of relational databases?
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What is the main purpose of an Entity Relationship (ER) Diagram?
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Which operation is NOT typically performed in a relational model?
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What problem can arise from complex relational database systems?
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Study Notes
When Not to Use a DBMS
- A DBMS is not recommended when the budget or expertise to operate a DBMS is lacking.
- In these situations, Excel/CSV/Flat Files can be suitable alternatives.
- For Web 2.0 applications, NoSQL DBMS is a better choice.
Database Architecture
- A Database Architecture represents the DBMS design.
- It aids in designing, developing, implementing, and maintaining the database management system.
- It allows for dividing the database system into independent components that can be modified, changed, replaced, and altered.
- The Database Architecture helps understand database components.
- Databases store critical information and facilitate secure and quick data access.
- Selecting the correct DBMS architecture is crucial for efficient data management.
Types of DBMS Architecture
- One Tier Architecture: Client, server, and database reside on the same machine. Often used for practice and rarely in production.
- Two Tier Architecture: Presentation layer runs on the client (PC, Mobile, Tablet, etc.), and data is stored on the server. Provides added security and faster communication.
- Three Tier Architecture: Presentation layer on the client, business logic on the application server, and data storage on the database server. Offers the most flexibility and scalability.
Referential Integrity Constraint
- It ensures that relationships between tables are maintained during data manipulation.
- It states that related key attributes in a table must exist in the referenced table.
Operations in Relational Model
- Insert Operation: Inserts new data into a relation.
- Delete Operation: Removes tuples from a table.
- Modify Operation: Changes attribute values in existing tuples.
- Select Operation: Retrieves specific data based on given conditions.
Best Practices for Creating a Relational Model
- Data should be represented as a collection of relations (tables).
- Each relation should be clearly depicted in a table.
- Rows should contain data about instances of an entity.
- Columns should contain data about attributes of the entity.
- Cells must hold a single value.
- All columns should have unique names.
- No two rows can be identical.
- Attribute values should be from the same domain.
Advantages of Relational Database Model
- Simplicity: Simpler than hierarchical and network models.
- Structural Independence: Focuses on data, not structure.
- Easy to use: Natural and easy to understand with tables.
- Query capability: Supports high-level query languages like SQL for efficient data retrieval.
- Data independence: Structure can be changed without altering applications.
- Scalability: Can be easily expanded for large datasets.
Disadvantages of Relational Database Model
- Limits on field lengths may exist.
- Complexity can increase with data growth and intricate relationships.
- Can lead to information isolation between systems.
Entity Relationship (ER) Diagram Model
- ER Diagram: Displays relationships between entity sets in a database.
- Helps to understand the logical structure of databases.
- Uses rectangles for entities, ovals for attributes, and diamonds for relationships.
- Serves as a visual representation of the entity framework infrastructure.
ER Model
- Represents real-world entities and their relationships.
- A best practice to systematically analyze data requirements before database implementation.
- Helps produce a well-designed database.
History of ER Models
- ER Diagrams were proposed by Peter Chen in 1971.
- Aimed to create a uniform convention for relational databases and networks.
- Intended as a conceptual modeling approach.
Why Use ER Diagrams?
- To better understand how SQL code works.
- To master understanding SQL queries.
SQL Commands
- Instructions used to communicate with a database.
- Used to perform specific tasks, functions, and data queries.
- Can be used for different functions like creating tables, adding data, dropping tables, modifying tables, and setting user permissions.
Types of SQL Commands
- SQL SELECT Statement: Used to retrieve data from a database.
- SQL FROM Statement: Specifies the table or tables from which data is retrieved.
- SQL WHERE Statement: Filters data based on specified conditions.
- SQL ORDER BY Statement: Sorts retrieved data in a specific sequence.
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Description
This quiz explores key concepts related to Database Management Systems (DBMS), including when not to use a DBMS, its architecture, and various types of DBMS architecture. Understanding these components is crucial for effective database design and data management.
