Multiple Choice Concepts

Question 1

Which SQL command is an example of data definition language (DDL)?

• UPDATE
• ALTER
• SELECT
• DELETE

Answer 1

The correct answer is:

ALTER

The ALTER command is an example of Data Definition Language (DDL) in SQL, which is used to define, modify, or delete database structures like tables and columns. Other DDL commands include CREATE, DROP, and TRUNCATE.

The other options are as follows:

UPDATE is a Data Manipulation Language (DML) command, used to modify data in existing records.
SELECT is a DML command used to retrieve data from a database.
DELETE is also a DML command, used to remove data from a table.

Question 2

Data Definition Language (DDL)

Answer 2

defines the structure of the database. CREATE, ALTER, DROP.

Question 3

Data Query Language (DQL)

Answer 3

retrieves data from the database. SELECT

Question 4

Data Manipulation Language (DML)

Answer 4

Manipulates data stored in a database. INSERT, UPDATE, DELETE.

Question 5

Data Control Language (DCL)

Answer 5

controls database user access.

Question 6

Data Transaction Language (DTL)

Answer 6

manages database transactions.

Question 7

How do you add a check statement into a table creation statement?

Answer 7

BirthDate DATE CHECK (BirthDate >= ‘2015-01-01’)

Question 8

INNER JOIN

Answer 8

selects only matching left and right table rows.

Question 9

FULL JOIN

Answer 9

selects all left and right table rows, regardless of match.

Question 10

LEFT JOIN

Answer 10

selects all left table rows, but only matching right table rows.

Question 11

RIGHT JOIN

Answer 11

selects all right table rows, but only matching left table rows.