Question

The symbol Asterisk (*) in a select query retrieves ____________. [1]

a) All data from the table

b) Data of primary key only

c) NULL data

d) iv) None of the mentione​

Answer 1

The symbol Asterisk (*) in a select query retrieves ____________option a) All data from the table

Explanation:

• The asterisk (*) in the select list indicates that all columns of the Book table should be included in the result set.
• Writing(*)is the same as listing all the columns the entity has.

Answer 2

The symbol Asterisk (*) in a select query retrieves All data from the table.

a) All data from the table

Extra Information

Query

A query helps us in requesting the data from table or tables of a database.

Example of an SQL query

SELECT * FROM table_name;

In this SELECT is used to select data from the database.

Asterisk (*) is used to retrieve all data from a table.

At the place of table_name, you can write the name of the table present in the database from which you want to retrieve the data.

Database

Database is stored in the computer system which has structured information in organized collections.

There are various types of databases such as

1) Centralized Database

2) Distributed Database

3) Relational Database

4) NoSQL Database

5) Cloud Database

6) Object-oriented Databases

7) Hierarchical Databases

8) Network Databases

Database Management System

Database Management Software is used to store data, retrieve the stored data, and also run queries on data to get specific data according to usage.

Key

A key is an attribute that helps us in identifying rows of a table.

There are many types of keys such as

1. Super Key

2. Primary Key

3. Candidate Key

4. Alternate Key

5. Foreign Key

6. Compound Key

7. Composite Key

8. Surrogate Key

Foreign Key

Foreign Key is used to create a link between two tables of the database. Foreign Key is also called referencing key because it refers to the primary key of the other table.

Primary Key

Primary Key helps us in identifying unique rows of a table.

Composite Key

Composite Key helps us in combining two or more columns of the table that helps us in identifying unique rows of the table.

Alternate Key

Alternate Key is the key that helps us in identifying unique rows of a table but, is not chosen as Primary Key.