1. CS122 Using Relational Databases and SQL*
CS122 Using Relational Databases and SQL
2. Single Table Queries
Randy Moss
Department of Computer Science
California State University, Los Angeles 1

2. Outline Recap Remove duplicates Create computed columns*
Outline
Recap
Remove duplicates
Create computed columns
Use multiple conditions in the where clause
Use wildcards
Sort query results
2. Single Table Queries CS1222_F2017
2-2 2

3. Recap SELECT column(s) FROM Tablename(s) WHERE condition(s)*
Recap
SELECT column(s)
FROM Tablename(s)
WHERE condition(s)
2. Single Table Queries CS1222_F2017
2-3 3

4. Recap show databases; show tables; describe Artists;*
Recap
show databases;
show tables;
describe Artists;
2. Single Table Queries CS1222_F2017
2-4 4

5. General SQL Tips
Generally not case sensitive for field names, SQL keywords and strings
Table names are CASE SENSITIVE in MySQL
Field and table names with spaces must be enclosed in ‘ ’
Field and table names that match SQL keywords must be enclosed in ‘ ’
2. Single Table Queries CS1222_F2017
2-5

6. Eliminate duplicate results*
Eliminate duplicate results
What are duplicates?
State CA VA
State
city CA
Burbank VA
Fairfax
Richmond
Sate
city
Street CA
Burbank
Main st. VA
Fairfax
Star st.
Richmond
Remove
Duplicates!
State CA VA
State
city CA
Burbank VA
Fairfax
Richmond
No Duplicates!
2. Single Table Queries CS1222_F2017
2-6 6

7. Eliminate duplicate results*
Eliminate duplicate results
Format
SELECT DISTINCT field1, field2,…
FROM Table
[WHERE] Conditions
Ex. List each city where a member lives, list each only once
SELECT DISTINCT region
FROM Members
2. Single Table Queries CS1222_F2017
2-7 7

8. Calculated Columns Columns can be derived from calculations*
Calculated Columns
Columns can be derived from calculations
The calculations use the the names of columns and constants
Assign names to columns with AS
Column alias
We focus on numeric calculations
2. Single Table Queries CS1222_F2017
2-8 8

9. Calculated Columns (cont)*
Calculated Columns (cont)
2. Single Table Queries CS1222_F2017
2-9 9

10. Calculated Columns (cont)*
Calculated Columns (cont)
List the track title and length in minutes of each track
SELECT tracktitle, lengthseconds/60 AS
lengthminutes
FROM Tracks
2. Single Table Queries CS1222_F2017
2-10 10

11. *
Two word column alias
Report all webaddresses in the Artists table, labeling the column Web Site
SELECT webaddress AS 'Web Site'
FROM Artists
Note: Aliases can NOT be used in the WHERE clause.
2. Single Table Queries CS1222_F2017
2-11 11

12. *
Basic Where Clauses
List the title and lengthseconds of every track that runs more than 240 seconds
SELECT tracktitle, lengthseconds
FROM Tracks
WHERE lengthseconds > 240
2. Single Table Queries CS1222_F2017
2-12 12

13. Comparison Operators Equal: = Not equal: <> Less than: <*
Comparison Operators
Equal: =
Not equal: <>
Less than: <
Greater than: >
Greater than or equal to: >=
Less than or equal to: <=
Attribute types that can be compared:
Numerical
Currency
Text
Date and Time
Generally speaking, different attribute types cannot compare to each other
2. Single Table Queries CS1222_F2017
2-13 13

14. Using Dates in Where Clauses*
Using Dates in Where Clauses
List the first name, last name and birthday of any member born on or after June 1, 1975
Select firstname, lastname, birthday
From Members
Where birthday>=' ';
2. Single Table Queries CS1222_F2017
2-14 14

15. Using Texts in Where Clauses*
Using Texts in Where Clauses
List the firstname and lastname of every member from Canada
SELECT firstname, lastname
FROM Members
WHERE country = 'Canada'
2. Single Table Queries CS1222_F2017
2-15 15

16. WHERE clauses with multiple conditions (AND & OR)*
WHERE clauses with multiple conditions (AND & OR)
Combine multiple conditions with AND, OR
AND: all conditions should be satisfied for a record to be reported
OR: If any conditions is true, the record is reported
SELECT fields
FROM Tables
WHERE (condition1) AND |OR
(condition 2) ……….
The more ANDs you use, the fewer records will be returned
The more ORs you use, the more records will be returned
2. Single Table Queries CS1222_F2017
2-16 16

17. *
And & Or (cont)
List the firstname, lastname, region and salesID of every member from Georgia who worked with salesperson 2
SELECT Firstname, Lastname, Region, SalesID FROM Members WHERE Region='GA’ and SalesID=2
2. Single Table Queries CS1222_F2017
2-17 17

18. And & Or (cont)
List the firstname, lastname, region and salesID of every member who is either from Georgia or who worked with salesperson 2
SELECT Firstname, Lastname, Region, SalesID FROM Members WHERE Region='GA' OR SalesID=2
2. Single Table Queries CS1222_F2017
2-18

19. *
And & Or (cont)
Parentheses can group conditions so they are treated as a unit
Should always use parentheses when mixing ANDs and Ors
Ex: list the firstname, lastname, region and salesid of every member who worked with salesperson 2 and is either from Georgia(GA) or Texas(TX).
2. Single Table Queries CS1222_F2017
2-19 19

20. And & Or (cont) Select Firstname, Lastname, Region, SalesID*
And & Or (cont)
Select Firstname, Lastname, Region, SalesID
From Members
Where Region='GA' Or Region='TX'
And SalesID=2
Select Firstname, Lastname, Region, SalesID
From Members
Where (Region='GA' Or Region='TX')
And SalesID=2
2. Single Table Queries CS1222_F2017
2-20 20

21. Booleans (True/False) Data Types in Where Clauses*
Booleans (True/False) Data Types in Where Clauses
List the tracktitles and realaud fields for all track records that do not have a real audio file
SELECT tracktitle, realaud
FROM Tracks
WHERE realaud = FALSE
Note: false NOT ‘FALSE’ (no quotes)
In MySQL, TRUE =1, FALSE=0
2. Single Table Queries CS1222_F2017
2-21 21

22. Like and Wildcards LIKE Wildcards*
Like and Wildcards
LIKE
Special keyword that tests for a group of letters anywhere in the field value.
Wildcards
_: stands for any single character
%: stands for any number of characters
2. Single Table Queries CS1222_F2017
2-22 22

23. Wildcard examples Mac MacIntosh Mackenzie LIKE 'Mac%'*
Wildcard examples
LIKE 'Mac%'
Mac MacIntosh Mackenzie
LIKE 'J%n'
Jon Johnson Jason Juan
LIKE 'Mac_'
Mack Macs
Anderson Johnson san sun
LIKE ‘%s_n’
2. Single Table Queries CS1222_F2017
2-23 23

24. Like List any track titles with the word ‘time’ anywhere in the title*
Like
List any track titles with the word ‘time’ anywhere in the title
SELECT TrackTitle
FROM Tracks
WHERE TrackTitle LIKE '%time%'
2. Single Table Queries CS1222_F2017
2-24 24

25. Wildcards can only be used with LIKE!*
Like (cont.)
Is the following correct?
SELECT TrackTitle
FROM Tracks
WHERE TrackTitle = '%time%'
Wildcards can only be used with LIKE!
2. Single Table Queries CS1222_F2017
2-25 25

26. Like (cont) List the website of any studio with a .com domain*
Like (cont)
List the website of any studio with a .com domain
SELECT webaddress
FROM Studios
WHERE webaddress Like ‘%.com'
2. Single Table Queries CS1222_F2017
2-26 26

27. Between Select values that fall between two values*
Between
Select values that fall between two values
Most often used with dates
Also works with numeric and text values
Inclusive of beginning & ending values
2. Single Table Queries CS1222_F2017
2-27 27

28. *
Between (cont.)
List the artist name and entry date for all artists with entry dates in August 2003
SELECT artistname, entrydate
FROM Artists
WHERE entrydate
BETWEEN ' ' AND ' '
Tests if field values matches any items in a list
List is placed inside parentheses
Individual items in list are separated by commas
Individual items also enclosed in appropriate characters if non-numeric
2. Single Table Queries CS1222_F2017
2-28 28

29. Is Null Tests for empty field values*
Is Null
Tests for empty field values
List the artists without a web page
SELECT Artistname
FROM Artists
WHERE WebAddress Is Null
2. Single Table Queries CS1222_F2017
2-29 29

30. In Test if the value of a field matches any items in a list* In
Test if the value of a field matches any items in a list
List is placed inside parentheses
Individual items in list are separated by commas
Individual items also enclosed in appropriate characters if non-numeric
SELECT fields
FROM Table
WHERE field IN (value1, value2,….)
2. Single Table Queries CS1222_F2017
2-30 30

31. *
In (cont.)
List the names, cities and regions of all members living in Indianna(IN), Illinois(IL), or Ohio(OH)
SELECT lastname, firstname, city, region
FROM Members
WHERE region IN ('IN', 'IL', 'OH')
2. Single Table Queries CS1222_F2017
2-31 31

32. Not Reverses the selection criterion*
Not
Reverses the selection criterion
Parentheses help indicate what Not applies to
SELECT fields
FROM Tables
WHERE NOT (conditions)
2. Single Table Queries CS1222_F2017
2-32 32

33. Not (cont.) List titles whose genre is not alternative Select *
From Titles
Where NOT (genre='alternative')
Where genre <>'alternative'
2. Single Table Queries CS1222_F2017
2-33 33

34. NOT (cont.)
List the artist name and web address of all artists who have a non-blank web address.
SELECT artistname, webaddress
FROM Artists
WHERE NOT (webaddress IS NULL)
SELECT artistname, webaddress
FROM Artists
WHERE webaddress IS NOT NULL
2. Single Table Queries CS1222_F2017
2-34

35. Order By Sorts the results Defaults to ascending (A-Z, 0-9)
Use DESC for descending (Z-A, 9-0)
Note proper order: SELECT – FROM - WHERE - ORDER BY
SELECT field1, field2,
FROM Tables
WHERE conditions
ORDER BY field1 [DESC], field2 [DESC],
2. Single Table Queries CS1222_F2017
2-35

36. Order By
List the title and genre of each title sorted by genre and then sorted within genre by title in descending order
SELECT title, genre
FROM Titles
ORDER BY genre, title DESC
2. Single Table Queries CS1222_F2017
2-36

37. Summary Calculated columns/ AS AND/OR BETWEEN DISTINCT IN IS NULL
LIKE/Wildcards
NOT
ORDER BY
2. Single Table Queries CS1222_F2017
2-37