Queries

Question 1

What is a core purpose of SQL?

Answer 1

To retrieve information stored in a database.

Question 2

What is retrieving information stored in a database usually referred to as?

Answer 2

Querying

Question 3

What type of statement would you use to only query data from two columns?

Answer 3

SELECT column1, column2
FROM table_name;

(SELECT statement)

Question 4

What keyword lets you rename a column or table using an alias?

Answer 4

AS

Question 5

Where must the new name in the AS keyword be placed in between?

Answer 5

Single quotes

’ ‘

Question 6

What would be used to find the distinct values of a particular column?

Answer 6

DISTINCT

Question 7

What does DISTINCT do?

Answer 7

Returns unique values in the output.

Question 8

What does DISTINCT filter out?

Answer 8

All duplicate values in the specified columns.

Question 9

Where does DISTINCT go in the SQL structure?

Answer 9

After the SELECT clause before the column name

SELECT DISTINCT ____
FROM _____;

Question 10

What clause can be used to restrict query results in order to obtain only the information wanted?

Answer 10

WHERE

Question 11

What does this statement do?

SELECT *
FROM movies
WHERE imdb_rating > 8;

Answer 11

The WHERE clause filters the result set to only include rows where the following condition is true
imdb_rating is the column
the > is the greater than operator
imdb_rating > 8 is a condition and only the rows with a value greater than 8 in the imdb_rating column will be returned.

Question 12

What comparison operators are used with WHERE clauses?

Answer 12

== (equal to)
!= (not equal to)
> (greater)
< (lesser)
>= (greater than or equal to)
<= (lesser than or equal to)

Question 13

What are Comparison Operators?

Answer 13

Operators create a condition that can be evaluated as either true or false.

Question 14

What special operator is used with the WHERE clause to search for a specific pattern in a column?

Answer 14

LIKE

(LIKE I)

Question 15

What is LIKE used for?

Answer 15

A useful operator to compare similar values.

Question 16

What does this statement do?

SELECT *
FROM movies
WHERE name LIKE ‘Se_en’;

Answer 16

LIKE is a special operator used with the WHERE clause to search for a specific patter in a column
name LIKE ‘Se_en’ is a condition evaluating the name column for a specific pattern
Se_en represents a patter with a wildcard character

Question 17

What wildcard character allows for individual character substitution without breaking the pattern?

Answer 17

_

Question 18

LIKE searches for a specific what in a column?

Answer 18

pattern

Question 19

What is a another wildcard character that can be used with LIKE that filters patterns?

Answer 19

%

Question 20

The wildcard character % matches ______ or _________ in a pattern?

Answer 20

zero
missing letters

Question 21

What does this statement do?

SELECT *
FROM movies
WHERE name LIKE ‘A%’;

Answer 21

‘A%’ matches all movies with names that begin with the letter ‘A’.

Question 22

What does this statement do?

SELECT *
FROM movies
WHERE name LIKE ‘%a’;

Answer 22

‘%a’ matches all movies that end with a ‘a’.

Question 23

What does this statement do?

SELECT *
FROM movies
WHERE name LIKE ‘%man%’;

Answer 23

Any movie that contains the word ‘man’ in its name will be returned in the result.

Question 24

True or False: LIKE is not case sensitive.

Answer 24

True

Question 25

What are unknown values indicated by?

Answer 25

NULL

Question 26

NULL values can not be tested with comparison operators = and !=. What operators are used as a replacement?

Answer 26

IS NULL IS NOT NULL

Question 27

What clause is the BETWEEN operator used in?

Answer 27

WHERE

Question 28

What does the BETWEEN operator do?

Answer 28

Filters the result set within a certain range.

Question 29

How many values does the BETWEEN operator accept?

Answer 29

Two

Question 30

What kind of data types are acceptable values for a BETWEEN operator?

Answer 30

Numbers Text Dates

Question 31

When the values are text, BETWEEN filers the result set for within what type of range?

Answer 31

Alphabetical

Question 32

What would be filtered out from this statement? SELECT * FROM movies WHERE name BETWEEN 'A' AND 'J';

Answer 32

Filters the result set to only include movies with the names that begin with the letter 'A' up to, but not including ones that begin with the letter 'J'.

Question 33

What would be filtered out from this statement? SELECT * FROM movies WHERE year BETWEEN 1990 AND 1999;

Answer 33

Filters the result set to only include movies with the years from 1990 up to and including 1999.

Question 34

What operator is used with the WHERE clause to combine multiple conditions?

Answer 34

AND

Question 35

Why would the AND operator be added in a WHERE clause?

Answer 35

To make the result set more specific and useful.

Question 36

What does this statement do? SELECT * FROM movies WHERE year BETWEEN 1990 AND 1999 AND genre = 'romance';

Answer 36

year BETWEEN 1990 AND 1999 is the 1st condition genre = 'romance' is the 2nd condition AND combines the two conditions

Question 37

True or False: With the AND operator, both conditions must be true for the row to be included in the result.

Answer 37

True

Question 38

Which operator in the WHERE clause displays a row if any condition is true?

Answer 38

OR

Question 39

What clause lists data in the result set in a particular order?

Answer 39

ORDER BY

Question 40

Which two ways can the results be sorted using ORDER BY?

Answer 40

Alphabetically Numerically

Question 41

What does this statement do? SELECT * FROM movies ORDER BY name;

Answer 41

ORDER BY is a clause that indicates you want to sort the result set by a particular column name is the specified column

Question 42

Is this statement sorting data in a decreasing or increasing order? SELECT * FROM movies WHERE imdb_rating > 8 ORDER BY year DESC;

Answer 42

Decreasing

Question 43

Which ORDER BY keyword sorts results from high to low or Z to A?

Answer 43

DESC

Question 44

Which ORDER BY keyword sorts results from low to high or A to Z?

Answer 44

ASC

Question 45

What is ASC and DESC in ORDER BY?

Answer 45

Keywords that stand for Ascending and Descending

Question 46

What clause does ORDER BY always go after? (If this clause is present).

Answer 46

WHERE

Question 47

What clause specifies a maximum number of rows the result will have?

Answer 47

LIMIT

Question 48

Where does the LIMIT clause go on a query?

Answer 48

At the very end

Question 49

What does this statement do? SELECT * FROM movies LIMIT 10;

Answer 49

LIMIT is a clause that lets you specify the maximum number of rows the result will have

Question 50

What is an advantage of the LIMIT clause?

Answer 50

Saves space on screen Queries run faster

Question 51

What type of statement allows for the creation of different outputs? (... consider it as an if-then logic)

Answer 51

CASE