SQL Fundamentals: Master the Basics of SQL for Database Management

Question 1

Which of the following is NOT a valid data type in SQL?

Accepted Answer

POINTER

Answer

INTEGER

Answer

VARCHAR

Answer

FLOAT

Question 2

Which data type is used to store whole numbers, without decimal places?

Accepted Answer

INTEGER

Answer

FLOAT

Answer

DECIMAL

Answer

VARCHAR

Question 3

Which comparison operator is used to determine if two values are equal?

Accepted Answer

=

Answer

!=

Answer

>

Answer

<

Question 4

Which SQL command is used to establish a new database table?

Accepted Answer

CREATE TABLE

Answer

INSERT INTO

Answer

UPDATE

Answer

DELETE

Question 5

Which of the following options is NOT a valid SQL table constraint?

Accepted Answer

IS NULL

Answer

PRIMARY KEY

Answer

FOREIGN KEY

Answer

UNIQUE

Question 6

What is the primary function of the 'WHERE' clause in an SQL statement?

Accepted Answer

To filter data based on specified conditions

Answer

To create a new table

Answer

To update existing data

Answer

To delete data

Question 7

Which data type in SQL is designed specifically for storing calendar dates?

Accepted Answer

DATE

Answer

DATETIME

Answer

TIME

Answer

TIMESTAMP

Question 8

What is the distinction between a primary key and a foreign key in SQL?

Accepted Answer

A primary key uniquely identifies each row in a table, while a foreign key references a primary key in another table

Answer

Both primary keys and foreign keys are used to maintain data integrity

Answer

Primary keys are optional, while foreign keys are mandatory

Answer

Foreign keys can be used to establish relationships between tables, while primary keys cannot

Question 9

What is the purpose of the 'GROUP BY' clause in an SQL statement?

Accepted Answer

To group rows that share similar values in one or more columns

Answer

To filter data based on specified conditions

Answer

To sort data in ascending or descending order

Answer

To create a new table

Question 10

Which SQL data type is designed specifically for storing dates?

Accepted Answer

DATE

Answer

INTEGER

Answer

NUMERIC

Answer

CHARACTER VARYING

Question 11

Which of the following is NOT a valid data type in SQL?

Accepted Answer

IMAGE

Answer

INT

Answer

CHAR

Question 12

Which SQL query retrieves all records from the 'orders' table where the 'order_date' is after a specific date and the 'order_status' is 'shipped'?

Accepted Answer

SELECT * FROM orders WHERE order_date > '2023-03-08' AND order_status = 'shipped';

Answer

SELECT * FROM orders WHERE order_date > 2023-03-08 OR order_status = 'shipped';

Answer

SELECT * FROM orders WHERE order_date = '2023-03-08' AND order_status = 'shipped';

Question 13

Which subquery correctly identifies customers who have placed multiple orders?

Accepted Answer

SELECT customer_name FROM customers WHERE order_id IN (SELECT order_id FROM orders GROUP BY customer_id HAVING COUNT(*) > 1)

Answer

SELECT customer_name FROM customers WHERE EXISTS (SELECT * FROM orders WHERE customer_id = customer_id)

Answer

SELECT customer_name FROM customers WHERE order_id > 1

Answer

SELECT customer_name FROM customers, orders WHERE customers.customer_id = orders.customer_id GROUP BY customer_name HAVING COUNT(*) > 1

Question 14

Which SQL data type is most appropriate for storing a date and time value?

Accepted Answer

TIMESTAMP

Answer

VARCHAR

Answer

DATE

Answer

CHAR

Question 15

Which comparison operator in SQL is used to determine if two values are equal?

Accepted Answer

=

Answer

>

Answer

<

Answer

<>

Question 16

In SQL, which command is used to create a new table?

Accepted Answer

CREATE TABLE

Answer

ALTER TABLE

Answer

DROP TABLE

Answer

INSERT INTO

Question 17

Which SQL clause is used to specify the criteria for selecting rows from a table?

Accepted Answer

WHERE

Answer

ORDER BY

Answer

GROUP BY

Answer

HAVING

Question 18

What is the primary purpose of a primary key in an SQL table?

Accepted Answer

To uniquely identify each row in the table

Answer

To enforce data integrity

Answer

To improve the performance of queries

Answer

To store metadata about the table

Question 19

Which SQL command is used to insert a new row into a table?

Accepted Answer

INSERT INTO

Answer

UPDATE

Answer

DELETE

Answer

SELECT

Question 20

In SQL, which command is used to modify the structure of an existing table?

Accepted Answer

ALTER TABLE

Answer

CREATE TABLE

Answer

DROP TABLE

Answer

UPDATE

Question 21

Which data type in SQL is used to store whole numbers without decimal places?

Accepted Answer

INTEGER

Answer

DECIMAL

Answer

FLOAT

Answer

NUMERIC

Question 22

Which operator in SQL is used to check if two values are equal?

Accepted Answer

=

Answer

<>

Answer

+

Answer

<

Question 23

Which command in SQL is used to create a new table?

Accepted Answer

CREATE TABLE

Answer

UPDATE

Answer

INSERT

Answer

SELECT

Question 24

Which command in SQL is used to retrieve data from a table?

Accepted Answer

SELECT

Answer

ADD

Answer

ALTER

Answer

DELETE

Question 25

Which command in SQL is used to modify data in a table?

Accepted Answer

UPDATE

Answer

DELETE

Answer

INSERT

Answer

ALTER

Question 26

Which command in SQL is used to remove data from a table?

Accepted Answer

DELETE

Answer

INSERT

Answer

ALTER

Answer

DROP

Question 27

What is the main purpose of the WHERE clause in an SQL statement?

Accepted Answer

To specify conditions for selecting data from a table

Answer

To update data in a table

Answer

To delete data from a table

Answer

To create a new table

Question 28

What is the key difference between an INNER JOIN and an OUTER JOIN in SQL?

Accepted Answer

An INNER JOIN only returns rows that have matching values in both tables, while an OUTER JOIN returns all rows from one table and matching rows from the other table

Answer

An INNER JOIN returns all rows from both tables, while an OUTER JOIN only returns matching rows

Question 29

What is a primary key in an SQL table primarily used for?

Accepted Answer

To uniquely identify each row in the table

Answer

To index the data in the table

Answer

To enforce a relationship between two tables

Answer

To store additional information about a row

Question 30

What is a foreign key in an SQL table primarily used for?

Accepted Answer

To establish a relationship between two tables

Answer

To store additional information about a row

Answer

To uniquely identify each row in the table

Answer

To index the data in the table