Relational Data Model Concepts Quiz

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Questions and Answers

Which term refers to the way data is organized within a database, including the arrangement of tables, columns, and relationships between them?

Schema (correct)

Foreign key

Primary key

Index

What type of relationship connects data in different tables by using primary and foreign keys to ensure data integrity and consistency?

One-to-many (correct)

One-to-one

One-to-all

Many-to-many

In a relational database, what do columns represent?

Data relationships

Database size

Individual data pieces (correct)

Data types

What are integrity constraints in a database?

Rules enforced on stored data for consistency Signup and view all the answers

Which SQL command is used to establish relationships between tables based on common attributes or keys?

JOIN Signup and view all the answers

What does the structure of a database define?

Data arrangement in tables Signup and view all the answers

What term is used in the relational data model to refer to a two-dimensional structure that stores data in rows and columns?

Relation Signup and view all the answers

Which term represents a single record or instance of data within a table in the relational data model?

Tuple Signup and view all the answers

What feature in a relational database uniquely identifies each row in a table?

Primary Key Signup and view all the answers

In the relational data model, what is the term used to define the kind of data that a column can store?

Attribute Signup and view all the answers

Which term enforces entity integrity by ensuring no duplicate or null values are allowed in a table?

Primary Key Signup and view all the answers

What is the term for a column or set of columns that refer to the primary key in another table in the relational data model?

Foreign Key Signup and view all the answers

What is the purpose of the SELECT statement in SQL?

To specify the columns you want to retrieve Signup and view all the answers

Which SQL keyword is used to limit the number of rows returned by a query?

LIMIT Signup and view all the answers

In a relational data model, what does a table represent?

A collection of rows Signup and view all the answers

Which SQL clause is used for filtering rows based on certain conditions?

HAVING Signup and view all the answers

What is the purpose of the GROUP BY clause in SQL?

To group the result set by columns Signup and view all the answers

Which SQL keyword is used to sort the result set based on one or more columns?

ORDER BY Signup and view all the answers

Study Notes

Relational Data Model Basics

A table (relation) is a 2D structure storing data in rows and columns, representing a single entity type (e.g., customers, products, employees).
Each table consists of rows and columns, with rows uniquely identified by a primary key.

Tuple (Row)

A row (tuple) represents a single record or instance of data within a table.
Each row contains data values for each column defined in the table.
Rows are uniquely identified by a primary key, ensuring each row is distinct.

Attribute (Column)

A column (attribute) represents a single piece of data within a table.
Each column has a name and a data type that defines the kind of data it can store (e.g., integer, string, date).
Columns define the structure of the data stored in the table.

Primary Key

A primary key is a column or a set of columns that uniquely identifies each row in a table.
It ensures each row is uniquely identifiable and serves as the primary means of accessing and referencing rows.
Primary keys enforce entity integrity by preventing duplicate or null values.

Foreign Key

A foreign key is a column or a set of columns in one table that refers to the primary key in another table.
It establishes relationships between tables based on common attributes or keys.

SELECT Statement

The basic syntax of a SELECT statement is: SELECT column1, column2,... FROM table_name;
The SELECT statement retrieves specified columns from a table.
Additional clauses can be used to filter, sort, or perform other operations on the result set:
- WHERE: filters rows based on certain conditions.
- ORDER BY: sorts the result set based on one or more columns.
- GROUP BY: groups the result set by one or more columns.
- HAVING: filters groups based on aggregate conditions.
- LIMIT: limits the number of rows returned by the query.