SQL

Question 1

Name this type of JOIN:

Answer 1

LEFT JOIN

Question 2

Name this type of JOIN:

Answer 2

FULL OUTER JOIN

Question 3

Name this type of JOIN:

Answer 3

INNER JOIN

Question 4

Name this type of JOIN:

Answer 4

RIGHT JOIN

Question 5

What is the name of the programming language designed to communicate with databases?

Answer 5

SQL

Question 6

SQL stores data in tables, also known as what?

Answer 6

relational database structures

Question 7

What SQL query is considered the most basic form?

Answer 7

SELECT

Question 8

What SQL statement is used to retrieve data from all columns in a table or to retrieve data from specified columns?

Answer 8

SELECT

Question 9

Fill in the blank: In order to get all all data from a customers table, use the _____ _ _____ query.

Answer 9

SELECT * FROM

Question 10

Scenario:

There is one table of data called “customers.” We need to get ids, first names, last names, and age from the “customers” table.

What query would we write to do this?

Answer 10

SELECT customer_id, first_name, last_name, customer_age

FROM customers

Question 11

What SQL clause filters results?

Answer 11

WHERE

Question 12

Scenario:

There is one table of data called “customers.” We want to get first names and last names from the table, but only of those customers who are less than 35 years old.

What query would we write to do this?

Answer 12

SELECT first_name, last_name

FROM customers

WHERE age < 35

Question 13

Scenario:

There is one table of data called “customers.” We want to get customer IDs from the table, but only for those who have the last name “Smith.”

What query would we write to do this?

Answer 13

SELECT customers_id

FROM customers

WHERE last_name = ‘Smith’

Question 14

Fill in the blank: _____ _____ is a SQL query used to sort data

Answer 14

ORDER BY

Question 15

What SQL query returns results in ascending order by default?

Answer 15

ORDER BY

Question 16

ORDER BY sorts query results in ascending order by default. What do you add to the statement in order to sort in descending order?

Answer 16

DESC

Question 17

Scenario:

You have a table of data called “customers.” You want to retrieve a list of all customers by first name and last name, ordered alphabetically by last name.

What query would you write to do this?

Answer 17

SELECT first_name, last_name

FROM customers

ORDER BY last_name

Question 18

Scenario:

You have a table called “customers.” You want to pull a list of customers’ last names, customer IDs, and ages. You only want customers under the age of 40 included in the last, and you want it ordered alphabetically by last name.

What query do you write to do this?

Answer 18

SELECT last_name, customer_id, ages

FROM customers

WHERE age < 40

ORDER BY last_name

Question 19

Scenario:

You have a table called “customers.” You want to pull all the data in the table, sorted by age in descending order.

What query do you write to do this?

Answer 19

SELECT *

FROM customers

ORDER BY age DESC

Question 20

What SQL command is used to only pull a small subset of data?

Answer 20

LIMIT

Question 21

What SQL command would you use to test out a query without pulling a large set of data?

Answer 21

LIMIT

Question 22

What are the three main data types in SQL?

Answer 22

INTEGER, TEXT, and BOOLEAN

Question 23

What category of SQL commands allow you to use math functions with your data?

Answer 23

Aggregators

Question 24

What SQL aggregator is used to find out how many records are in a data set?

Answer 24

COUNT

Question 25

What SQL aggregator is used to add up the total value of a set of numeric values?

Answer 25

SUM

Question 26

What SQL aggregator is used to find the mean of a set of numeric values?

Answer 26

AVG

Question 27

What SQL query word is used to create columns in your table using results from an aggregator command, or just to rename an existing column in the table?

Answer 27

as

Question 28

Scenario:

You have a table called “customers.” You want to discover the average number of orders per customer (under the “order_count” column).

What querty do you write to do this?

Answer 28

SELECT AVG(order_count)

FROM customers

Question 29

Scenario:

You have a table called “customers.” You want to generate a list of data from the table, telling you how many customers there are (each customer has a unique ID).

What query do you write to do this?

Answer 29

SELECT COUNT(customer_id)

FROM customers

Question 30

Scenario:

You have a table called “customers.” The table has a row for each order (and each order has its own order ID), even if the customer has ordered multiple times. You want to create a column that shows the total number of orders that customer (identified by their customer ID) has placed.

What query do you write to do this?

Answer 30

SELECT COUNT(order_id)

as customer_order_total

FROM customers

Question 31

Scenario:

You have a table called “customers.” In this table is a column featuring a unique string of numbers assigned to every order. It is called “order_identity.” Because customers are also assigned a unique string and this column is called “customer_id,” you want to rename the order column “order_id.”

What querty do you write to do this?

Answer 31

SELECT order_identity

as order_id

FROM customers