Data Definition Language (DDL)

Question 1

Which constraint automatically generates sequential values for a column, typically used for IDs?

A.

A) **AUTO_INCREMENT**

**Explanation:** **AUTO_INCREMENT** ensures unique, incrementing integers without manual specification.

B.

B) UNIQUE

C.

C) DEFAULT

D.

D) CHECK

Question 2

What is stored in the **data dictionary** of a database?

A.

A) Actual data rows from tables

B.

B) Query results from SELECT statements

C.

C) Table definitions including columns, data types, and constraints

Explanation: The data dictionary holds metadata such as table structure, columns, data types, sizes, and constraints.

D.

D) Temporary data during transactions

Question 3

What does the **data dictionary** store regarding inter-table relationships?

A.

A) Actual row values

B.

B) Foreign key definitions

Explanation: It includes relationships like foreign keys linking tables such as Employees.DeptID to Departments.DeptID.

C.

C) Inserted data rows

D.

D) Query execution plans

Question 4

What is the primary purpose of the **ALTER TABLE** command?

A.

A) To delete a table

B.

B) To modify an existing table structure

**Explanation:** ALTER TABLE is a DDL statement used to change table definitions after creation, such as adding or modifying columns.

C.

C) To insert data into a table

D.

D) To query data from a table

Question 5

You need to rename the **Employees** table to **Staff**. Which statement accomplishes this?

A.

A) ALTER TABLE Employees RENAME TO Staff;

Explanation: The syntax **ALTER TABLE old_table_name RENAME TO new_table_name** is used to rename entire tables. Option A uses incorrect syntax, and Options C and D are not valid rename operations.

B.

B) RENAME TABLE Employees TO Staff;

C.

C) ALTER TABLE Employees CHANGE TO Staff;

D.

D) UPDATE TABLE Employees SET name = Staff;

Question 6

Which DDL command is used to remove all rows from a table while preserving its structure?

A.

A) DROP TABLE

B.

B) DELETE FROM

C.

C) TRUNCATE TABLE

Explanation: TRUNCATE TABLE removes all data from a table instantly but keeps the table structure intact. DELETE FROM can also remove rows but is slower and generates individual delete logs.

D.

D) ALTER TABLE

Question 7

Which SQL statement is used to create a new table?

A.

A) ALTER TABLE

B.

B) DROP TABLE

C.

C) CREATE TABLE

Explanation:**CREATE TABLE** defines a new table with columns, data types, and constraints.

D.

D) TRUNCATE TABLE

📝 Data Definition Language (DDL)

Quiz Complete!