Understanding Relational Data Models: SQL

In a class project, Michael is trying to explain to his classmates what a relational data model is.

• A relational data model is a programming language for database management.

• A relational data model is a way to structure data using tables that represent entities and their relationships.

• A relational data model uses graphs to represent data relationships.

• A relational data model is a method for storing data in a single file.

Answer explanation

The correct choice describes a relational data model as a structure using tables to represent entities and their relationships, which is fundamental to how relational databases organize data.

Elijah is learning about databases in his computer science class. Define a table in the context of a relational database.

• A table is a collection of unrelated data points.

• A table is a single row of data in a database.

• A table is a structured collection of data organized in rows and columns in a relational database.

• A table is a graphical representation of data in a database.

Answer explanation

A table in a relational database is a structured collection of data organized in rows and columns, allowing for efficient data management and retrieval. This definition distinguishes it from unrelated data points or graphical representations.

In a school database, what is a field in a relational database table?

• A field is a command used to query a database.

• A field is a column in a relational database table that holds data for a specific attribute.

• A field is a type of database that stores multiple tables.

• A field is a row in a relational database table.

Answer explanation

A field in a relational database table refers to a column that contains data for a specific attribute, distinguishing it from rows, which represent individual records. This makes the correct choice the second option.

Avery is learning about databases in her computer science class. She wants to understand what a row represents in a relational database.

• A row represents a column in a relational database table.

• A row represents a single record in a relational database table.

• A row is a type of database query.

• A row contains metadata about the database structure.

Answer explanation

A row in a relational database table represents a single record, containing all the data attributes for that specific entry. This distinguishes it from columns, which represent the attributes themselves.

In a database project for their class, Rohan and Kai are discussing the structure of a relational table. What does the term 'degree' refer to in a relational table?

• The total number of rows in a relational table.

• The number of attributes (columns) in a relational table.

• The type of data stored in each column of a relational table.

• The unique identifier for each row in a relational table.

Answer explanation

In a relational table, the term 'degree' refers to the number of attributes (columns). This is distinct from the number of rows or the type of data, making the correct choice the second option.

Mia is studying relational databases in her computer science class. She wants to understand the concept of cardinality. Can you help her define it?

• Cardinality refers to the total number of rows in a table.

• Cardinality is the process of indexing data for faster retrieval.

• Cardinality defines the data types allowed in a column.

• Cardinality defines the uniqueness of data values in a column and the relationships between tables in a relational database.

Answer explanation

Cardinality in relational databases refers to the uniqueness of data values in a column and the relationships between tables. It helps define how many unique values exist and how tables relate to each other.

Arjun wants to create a new table in his database to store student information. How does he do it in SQL?

• ALTER TABLE table_name ADD column_name column_datatype;

• DROP TABLE table_name;

• INSERT INTO table_name (column1_name, column2_name);

• CREATE TABLE table_name (column1_name column1_datatype, column2_name column2_datatype, ...);

Answer explanation

To create a new table in SQL, you use the statement 'CREATE TABLE table_name (column1_name column1_datatype, column2_name column2_datatype, ...);'. This defines the table structure, unlike the other options which serve different purposes.

During a class project, Daniel needs to modify the structure of a database table. What SQL command should he use to modify an existing table?

• DROP TABLE

• ALTER TABLE

• CREATE TABLE

• UPDATE TABLE

Answer explanation

The correct command to modify an existing table in SQL is 'ALTER TABLE'. This command allows you to add, delete, or modify columns in a table. 'DROP TABLE' removes a table, 'CREATE TABLE' creates a new one, and 'UPDATE TABLE' is not a valid SQL command.

Lily is studying SQL for her database class. Can you list the main components of SQL that she should focus on?

• DQL, DDL, DML, and DFL

• DQL, DDL, DML, and DCLT

• The main components of SQL are DQL, DDL, DML, and DCL.

• DQL, DDL, DML, and DCLX

Answer explanation

The correct answer identifies the main components of SQL as DQL (Data Query Language), DDL (Data Definition Language), DML (Data Manipulation Language), and DCL (Data Control Language). Other options include incorrect terms.

Nora is trying to understand how to manage data in her new database. What is the purpose of the SELECT statement in SQL?

• To create new tables in a database.

• To delete data from a database.

• To update existing records in a database.

• To retrieve data from a database.

Answer explanation

The SELECT statement in SQL is specifically designed to retrieve data from a database. It allows users to query and fetch specific information, making it essential for data retrieval.