SQL

Question 1

Is SQL a case-sensitive language?

Answer 1

No

Question 2

Every statement must be terminated with:

Answer 2

A semi-colon (;)

Question 3

How do you add a comment?

Answer 3

Add “–” before

Question 4

Order of operations?

Answer 4

Parentheses
Multiplication / division
Addition / subtraction

Question 5

SELECT clause

Answer 5

Returns a result set of records from one or more tables

Most commonly used DML command

Question 6

SELECT DISTINCT

Answer 6

Removes duplicate values

Question 7

WHERE clause

Answer 7

Used to filter data

Question 8

Comparison Operators

Answer 8

> , >=

!=

Question 9

Logical Operators

Answer 9

Used with WHERE clause

AND (both conditions must be True)

OR (at least one condition must be True)

NOT (to negate a condition)

Question 10

IN Operator

Answer 10

Returns values in any of specified values

Example:
WHERE state IN (‘VA’, ‘NY’, ‘CA’)

Question 11

BETWEEN Operator

Answer 11

WHERE points BETWEEN 100 AND 200

Inclusive of the values provided

Question 12

LIKE Operator

Answer 12

Used in the WHERE clause to search for a specified pattern in a column

Question 13

WHERE first_name LIKE ‘b%’

WHERE first_name LIKE ‘%b’

WHERE first_name LIKE ‘b___’

Answer 13

First name starts with b and has any number of characters

First name ends with b and has any number of characters

First name starts with b and ends with exactly 3 characters

Question 14

WHERE first_name REGEXP ‘ey$|on$’

Answer 14

Returns first names that end with EY or ON

Question 15

WHERE first_name REGEXP ‘^a’

Answer 15

Returns first names that start with ‘a’

Question 16

WHERE first_name REGEXP ‘^my|se’

Answer 16

Returns first names that start with MY or contain SE

Question 17

WHERE first_name REGEXP ‘b[ru]’

Answer 17

Returns first names that contain B followed by R or U

Question 18

IS NULL Operator

Answer 18

Returns records that are null/don’t contain any data

Question 19

ORDER BY Clause

Answer 19

Sorts values in ascending order by default

DESC at end of ORDER BY clause to specify descending order

Question 20

LIMIT Clause

Answer 20

Returns only a specified number of values

Question 21

LIMIT 6, 3

Answer 21

Skips first 6 entries and returns numbers 7, 8, 9

Question 22

JOIN (INNER JOIN)

Answer 22

Returns all records that have matching values in both tables

Question 23

LEFT JOIN

Answer 23

Returns all records from the left table, and the matched records from the right table

Question 24

RIGHT JOIN

Answer 24

Returns all records from the right table, and the matched records from the left table

Question 25

USING Clause

Answer 25

If column names are identical, you can simplify the join with the USING clause

SELECT *
FROM customers c
JOIN orders o
USING (customer_id)

Question 26

CROSS JOIN

Answer 26

Combine every value in one table with every value in the other table (color and size)

SELECT *
FROM colors
CROSS JOIN sizes

Question 27

UNION

Answer 27

Combine records from multiple result sets

SELECT name, address
FROM customers
UNION
SELECT name, address
FROM clients

Question 28

Insert a single record

Answer 28

INSERT INTO customers(first_name, phone, points)

VALUES (‘Hannah’, NULL, DEFAULT)

Question 29

Insert multiple records

Answer 29

INSERT INTO customers(first_name, phone, points)
VALUES
(‘Hannah, NULL, DEFAULT),
(‘Bob’, ‘1234’, 10)