Data definition language - MySQL - Quiz

Q: Which DDL statement is used to add a unique constraint to a column in MySQL?

A. ADD UNIQUE
B. CREATE UNIQUE
C. UNIQUE KEY
D. ALTER CONSTRAINT

Correct Option: C
Explanation:

The UNIQUE KEY statement in MySQL is used to add a unique constraint to a column in a table. It ensures that the values in the column are unique across all rows.

Q: Which DDL statement is used to add a foreign key constraint to a table in MySQL?

A. ADD CONSTRAINT
B. CREATE CONSTRAINT
C. FOREIGN KEY
D. ALTER TABLE

Correct Option: C
Explanation:

The FOREIGN KEY statement in MySQL is used to add a foreign key constraint to a table. It establishes a relationship between two tables based on a column or set of columns.

Q: Which of the following DDL statements is used to create a new database in MySQL?

A. CREATE DATABASE
B. ALTER DATABASE
C. ADD DATABASE
D. MAKE DATABASE

Correct Option: A
Explanation:

The CREATE DATABASE statement in MySQL is used to create a new database. It specifies the name of the database and optional character set and collation settings.

Q: Which of the following is a valid ALTER statement in MySQL?

A. ALTER INDEX
B. ALTER VIEW
C. ALTER SELECT
D. ALTER DELETE

Correct Option: B
Explanation:

The ALTER VIEW statement in MySQL is used to modify the definition of a view, such as changing the columns displayed or the underlying SELECT statement.

Q: Which of the following DDL statements is used to create a new view in MySQL?

A. CREATE INDEX
B. ALTER VIEW
C. CREATE VIEW
D. ADD VIEW

Correct Option: C
Explanation:

The CREATE VIEW statement in MySQL is used to create a new view. A view is a virtual table derived from one or more tables or other views, which can be queried like a regular table.

Q: Which of the following statements is true about Data Definition Language (DDL) in MySQL?

A. DDL is used to retrieve data from the database.
B. DDL is used to define and modify the structure of the database objects.
C. DDL is used to perform mathematical calculations on the data.
D. DDL is used to filter and sort the data in the database.

Correct Option: B
Explanation:

DDL in MySQL is used to define and modify the structure of database objects such as tables, views, indexes, and constraints. It includes statements like CREATE, ALTER, and DROP to create, modify, or delete the database objects.

Q: Which DDL statement is used to rename a table in MySQL?

A. ALTER TABLE
B. RENAME TABLE
C. MODIFY TABLE
D. UPDATE TABLE

Correct Option: B
Explanation:

The RENAME TABLE statement in MySQL is used to rename a table. It allows you to change the name of an existing table in the database.

Q: Which DDL statement is used to remove a column from an existing table in MySQL?

A. DROP COLUMN
B. DELETE COLUMN
C. REMOVE COLUMN
D. ALTER COLUMN

Correct Option: A
Explanation:

The DROP COLUMN statement in MySQL is used to remove a column from an existing table. It permanently deletes the specified column and its associated data from the table.

Q: Which DDL statement is used to change the name of an existing column in MySQL?

A. MODIFY COLUMN
B. RENAME COLUMN
C. UPDATE COLUMN
D. CHANGE COLUMN

Correct Option: D
Explanation:

The CHANGE COLUMN statement in MySQL is used to change the name of an existing column in a table. It allows you to specify the current column name and the new column name.

Q: Which of the following statements is true about the DROP statement in MySQL?

A. DROP is used to delete data from a table.
B. DROP is used to delete a database.
C. DROP is used to delete a specific column from a table.
D. DROP is used to delete a table or other database objects.

Correct Option: D
Explanation:

The DROP statement in MySQL is used to delete a table, view, index, or other database objects. It permanently removes the specified object from the database.