1

SQL by Example

2

SQL: What is it?

• SQL stands for Structured Query Language.• It was originally developed in the early 1970s

by IBM as a way to manipulate and retrieve data stored in IBM’s relational DBMS, System R.

• It can be pronounced “Sequel” or “S-Q-L”.• With some variations, SQL is the standard

query language for relational databases.

3

When do we use SQL?

• SQL is most commonly used to retrieve data from a database.

• It is also commonly used to modify data.• SQL also contains commands for creating

tables and other database objects, and for maintaining data security through granting and denying privileges to users.

4

SQL is Intuitive

• To show how easy it is to learn SQL, we’ll start out simply using examples.

• We’ll review what you see in the examples in upcoming lectures.

5

Players Table

• SELECT LastName FROM Players WHERE PlayerID = 8• SELECT Position FROM Players WHERE LastName =

‘Schrute’• SELECT Age FROM Players WHERE FirstName =

‘Dwight’

6

Answers

• SELECT LastName FROM Players WHERE PlayerID = 8– Jennings

• SELECT Position FROM Players WHERE LastName = ‘Schrute’– Left Field

• SELECT Age FROM Players WHERE FirstName = ‘Dwight’– 27

7

Trick Question

• SELECT PlayerID FROM Players WHERE LastName = ‘Johnson’

8

• SELECT PlayerID FROM Players WHERE LastName = ‘Johnson’

Query1PlayerID

1517

9

• SELECT PlayerID FROM Players WHERE Position = 'AH'

10

• SELECT PlayerID• FROM Players WHERE Position = 'AH'

Query1PlayerID

11172231

11

• SELECT FirstName, LastName, Age FROM Players WHERE Position = 'Pitcher'

12

• SELECT FirstName, LastName, Age FROM Players WHERE Position = 'Pitcher'

Query1FirstName LastName AgeWalter Williams 40Derrick Markel 28Tim Ford 29

13

• SELECT * FROM Players WHERE PlayerID = 1

14

• SELECT * FROM Players WHERE PlayerID = 1

Query1PlayerID LastName FirstName Age Position PhoneNumber TeamID

1 Cage Nick 25 1st Base (734)431-9880 1

15

• SELECT * FROM Players WHERE Position = 'Catcher'

16

• SELECT * FROM Players WHERE Position = 'Catcher'

Query1PlayerID LastName FirstName Age Position PhoneNumber TeamID

10 Gomez Felipe 36 Catcher (734)697-4356 116 Sherman Mike 28 Catcher (734)607-0436 234 Malone Kevin 26 Catcher (734)695-9019 3

17

• SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE Age < 22

18

• SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE Age < 22

Query1PlayerID FirstName LastName Age

8 Greg Jennings 2130 Hector Gonzales 21

19

• SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND Age>35

20

• SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND Age>35

Query1PlayerID FirstName LastName Age

7 Walter Williams 4010 Felipe Gomez 3611 Chris Swanson 36

21

• SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND Age>37 OR Position='1st Base'

22

Query1PlayerID FirstName LastName Age

1 Nick Cage 257 Walter Williams 40

21 Joey Szarek 3725 Justin Fleeson 33

• SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND Age>37 OR Position='1st Base'

23

Elements Table

SELECT symbol FROM elements WHERE grp=13 AND period=4

24

SELECT symbol FROM elements WHERE grp=13 AND period=4

Query1

symbol grp periodGa 13 4

25

SELECT symbol FROM elements WHERE grp=13 OR period=4

26

• SELECT symbol,grp,period FROM elements WHERE grp=13 OR period=4

Query1symbol grp periodAl 13 3As 15 4B 13 2Br 17 4Ca 2 4Co 9 4Cr 6 4Cu 11 4Fe 8 4Ga 13 4Ge 14 4In 13 5K 1 4Kr 18 4Mn 7 4Ni 10 4Sc 3 4Se 16 4Ti 4 4Tl 13 6Uut 13 7V 5 4Zn 12 4

27

• SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND (Age>37 OR Position='1st Base') ORDER BY Age

28

• SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND (Age>37 OR Position='1st Base') ORDER BY Age

Query1PlayerID FirstName LastName Age

1 Nick Cage 257 Walter Williams 40

29

You are the DBMS

• In these exercises, you are acting like the DBMS.

• All major DBMS’s have SQL interpreters.• You can submit queries like these to a

database and the DBMS will find the matching results for you.

30

Trick Question!

• SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND (Age>37 AND Position='1st Base') ORDER BY Age

31

• SELECT PlayerID, FirstName, LastName, Age FROM Players WHERE TeamID=1 AND (Age>37 AND Position='1st Base') ORDER BY Age

32

• SELECT * FROM Beings WHERE BirthYear>17

33

Query1BeingID BeingName HomePlanetID BirthYear

6 Obiwan 3 1912 Ohuru 1 1913 Scott 5 19

• SELECT * FROM Beings WHERE BirthYear>17

34

• SELECT * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear

35

Query1BeingID BeingName HomePlanetID BirthYear

15 Armstrong 1 220 Ilya 1 416 Fred 1 5

1 Luke 1 122 Leia 1 17

12 Ohuru 1 19

• SELECT * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear

36

• SELECT * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear ASC

37

Query1BeingID BeingName HomePlanetID BirthYear

15 Armstrong 1 220 Ilya 1 416 Fred 1 5

1 Luke 1 122 Leia 1 17

12 Ohuru 1 19

• SELECT * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear ASC

38

SELECT * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear DESC

39

Query1BeingID BeingName HomePlanetID BirthYear

12 Ohuru 1 192 Leia 1 171 Luke 1 12

16 Fred 1 520 Ilya 1 415 Armstrong 1 2

SELECT * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear DESC

40

SELECT * FROM Beings WHERE BirthYear BETWEEN 11 AND 15

41

SELECT * FROM Beings WHERE BirthYear BETWEEN 11 AND 15

Query1BeingID BeingName HomePlanetID BirthYear

1 Luke 1 127 Chewbaca 5 128 Anakin 4 11

23 Bob 2 12

42

SELECT Symbol, Element, AtomicNumber, AtomicMass, AtomicMass / AtomicNumber AS WeightRatio FROM Elements WHERE Grp = 4

43

Query1Symbol Element AtomicNumber AtomicMass WeightRatioHf Hafnium 72 178.49 2.47902774810791Rf Rutherfordium 104 261 2.50961542129517Ti Titanium 22 47.867 2.17577266693115Zr Zirconium 40 91.224 2.28060007095337

SELECT Symbol, Element, AtomicNumber, AtomicMass, AtomicMass / AtomicNumber AS WeightRatio FROM Elements WHERE Grp = 4

44

SELECT TOP 1 * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear

45

SELECT TOP 1 * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear

Query1BeingID BeingName HomePlanetID BirthYear

15 Armstrong 1 2

46

• SELECT TOP 1 * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear DESC

47

• SELECT TOP 1 * FROM Beings WHERE HomePlanetID = 1 ORDER BY BirthYear DESC

Query1BeingID BeingName HomePlanetID BirthYear

12 Ohuru 1 19

48

SELECT TOP 3 * FROM Beings ORDER BY BeingName

49

Query1BeingID BeingName HomePlanetID BirthYear

8 Anakin 4 1115 Armstrong 1 223 Bob 2 12

SELECT TOP 3 * FROM Beings ORDER BY BeingName

50

SELECT * FROM Elements WHERE AtomicNumber BETWEEN 80 AND 90 ORDER BY AtomicNumber DESC

51

Query1

Symbol Element AtomicNumber AtomicMass Grp Period Series

Th Thorium 90 232.0381 0 7 ActinideAc Actinium 89 227 0 7 ActinideRa Radium 88 226 2 7 Alkaline earth metal

Fr Francium 87 223 1 7 Alkali(metal)

Rn Radon 86 220 18 6 Noble gasAt Astatine 85 210 17 6 HalogenPo Polonium 84 210 16 6 MetalloidBi Bismuth 83 208.9804 15 6 Poor metalPb Lead 82 207.2 14 6 Poor metalTl Thallium 81 204.3833 13 6 Poor metalHg Mercury 80 200.59 12 6 Transition metal

SELECT * FROM Elements WHERE AtomicNumber BETWEEN 80 AND 90 ORDER BY AtomicNumber DESC

52

SELECT COUNT(*) AS NumberOfElements FROM Elements

53

Query1NumberOfElements

117

SELECT COUNT(*) AS NumberOfElements FROM Elements

54

SELECT Series, COUNT(*) AS NumberOfElements FROM Elements GROUP BY Series ORDER BY Series

55

Query1Series NumberOfElementsActinide 15Alkali(metal) 6Alkaline earth metal 6Halogen 5Lanthanide 15Metalloid 7Noble gas 7Nonmetal 7Poor metal 11Transition metal 38

SELECT Series, COUNT(*) AS NumberOfElements FROM Elements GROUP BY Series ORDER BY Series

56

SELECT Period, MAX(AtomicNumber) AS MaxAtNum FROM Elements GROUP BY Period ORDER BY Period

57

Query1Period MaxAtNum

1 22 103 184 365 546 867 118

SELECT Period, MAX(AtomicNumber) AS MaxAtNum FROM Elements GROUP BY Period ORDER BY Period