Structured Query Language (SQL)

Question 1

What are the main components of SQL?

Answer 1

DDL, DML, DCL, and embedded SQL

Question 2

What does the DECIMAL(P, S) data type mean?

Answer 2

P = total digits, S = digits after decimal (e.g., DECIMAL(5,2) → 999.99)

Question 3

What is the function of a CHECK constraint?

Answer 3

Ensures that a column’s value meets a specific condition or range

Question 4

How do you define a composite primary key?

Answer 4

List multiple columns in the PRIMARY KEY constraint separated by commas

Question 5

Which keyword is used to change an existing table?

Answer 5

ALTER TABLE

Question 6

What is the default referential integrity enforcement if not specified?

Answer 6

RESTRICTION

Question 7

Difference between CHAR and VARCHAR?

Answer 7

CHAR is fixed length (padded), VARCHAR is variable (saves space)