database systems cse 303 lecture 03:...

Database SystemsCSE 303

Lecture 03: SQL

1

2016

Single Table Query

CSE 303: Ashikur Rahman

SQL

• Data Definition Language (DDL)

– Create/alter/delete tables and their attributes

– Following lectures...

2

– Following lectures...

• Data Manipulation Language (DML)

– Query one or more tables – discussed next !

– Insert/delete/modify tuples in tables


Tables in SQL

PName Price Category Manufacturer

Gizmo $19.99 Gadgets GizmoWorks

Product

Attribute namesTable name

3


Powergizmo $29.99 Gadgets GizmoWorks

SingleTouch $149.99 Photography Canon

MultiTouch $203.99 Household Hitachi

Tuples or rows CSE 303: Ashikur Rahman

SQL Query

Basic form: (plus many many more bells and whistles)

4

Basic form: (plus many many more bells and whistles)

SELECT <attributes>FROM <one or more relations>


Simplest SQL Query





Product

5



Show all entries from product table


Simplest SQL Query






Product

6


SELECT *FROM Product

“selection”





MultiTouch $203.99 Household HitachiCSE 303: Ashikur Rahman

Single Column Selection






Product

Show all product categories

7


SELECT categoryFROM Product

Category

Gadgets

Gadgets

Photography

Household

“selection” and“projection”


Single Column Selection (Eliminating Duplicates)






Product

8


SELECT DISTINCT categoryFROM Product

Category

Gadgets

Photography

Household


Show all product categories

In summary..

SELECT DISTINCT categoryFROM Product

Category

Gadgets

Photography

Household

99

Compare to:

SELECT categoryFROM Product

Category

Gadgets

Gadgets

Photography

Household


Multi-column Selection






Product

List all products along with their price and manufacturers

10


SELECT pname, price, manufacturerFROM Product

PName Price Manufacturer

Gizmo $19.99 GizmoWorks

Powergizmo $29.99 GizmoWorks

SingleTouch $149.99 Canon

MultiTouch $203.99 HitachiCSE 303: Ashikur Rahman

Notation

Product(PName, Price, Category, Manfacturer)

Input Schema

11

Product(PName, Price, Category, Manfacturer)

Answer(PName, Price, Manfacturer)

Output Schema

SELECT pname, price, manufacturerFROM Product


Duplicates from multiple columnMaker Model Type

A 1001 pc

A 1002 pc

A 1003 pc

A 2004 laptop

A 2005 laptop

SELECT maker, typeFROM Product

1212

A 2005 laptop

A 2006 laptop

B 1004 pc

B 1005 pc

B 1006 pc

B 2007 laptop

C 1007 pc

… … …

…. … …

?CSE 303: Ashikur Rahman

Duplicates from multiple column

SELECT maker, typeFROM Product

Maker Type

A pc

A pc

A pc

A laptop

A laptop

1313CSE 303: Ashikur Rahman

A laptop

A laptop

B pc

B pc

B pc

B laptop

C pc

… …

…. …

Duplicates from multiple columnMaker Type

A pc

A pc

A pc

A laptop

A laptop

SELECT DISTINCT maker, typeFROM Product

1414

A laptop

A laptop

B pc

B pc

B pc

B laptop

C pc

… …

…. …


Duplicates from multiple columnMaker Type

A pc

A laptop

B pc

B laptop

C pc

1515

C pc

… …

…. …

… …

…. …

… …

…. …

… …

…. …


Simple Predicates

1616

SELECT <attributes>FROM <one or more relations>WHERE <conditions>

1

2

3


Semantics

SELECT a1,…,ak

FROM RWHERE conditions

1

2

3

1717CSE 303: Ashikur Rahman

Answer = {}for each x in R do

if conditions satisfied thenAnswer = Answer {(a1,…,ak)}

return Answer

Number Range Selection






Product

Show all product’s info that will cost more than 100 dollars

1818


SELECT *FROM ProductWHERE price > 100





Answer = {}for each x in R do

if conditions satisfied thenAnswer = Answer {(a1,…,ak)}

return Answer

Number Range Operators

• Greater than “>”

• Less than “<”

19

• Less than “<”

• Greater than or equal to “>=”

• Less than or equal to “<=”

• Two forms of not-equal-to

“!=” and “< >”


BETWEEN-AND operator






Product

Show all product categoriesShow all product’s info in the price range $100 to $200 (inclusive)

2020


SELECT *FROM ProductWHERE price BETWEEN 100 AND 200


SingleTouch $149.99 Photography CanonBETWEEN-ANDis inclusive


String Matching






Product

Show all household product’s info

2121


SELECT pname, price, manufacturerFROM ProductWHERE category =‘Household’

PName Price Manufacturer

MultiTouch $203.99 Hitachi


Matches even category is fixed length CHAR data type right padded with blank

The LIKE operator

• s LIKE p: pattern matching on strings

• p may contain two special symbols:

(1) % any sequence of characters (zero or more)

22

(1) % any sequence of characters (zero or more)

(2) _ any single character (exactly one)


The LIKE operator






Show all product’s info that has ‘mo’ as a substring of the product name

23

SELECT *FROM ProductsWHERE pname LIKE ‘%mo%’





The LIKE operator






Show all product’s info where the product name ends with ‘Touch’

24

SELECT *FROM ProductsWHERE pname LIKE ‘%Touch’





The LIKE operatorPName Price Category Manufacturer





25

SELECT *FROM ProductsWHERE manufacturer LIKE ‘G_z_oWorks’





Searching for three special symbols

• ’ ‘Baby’s World’

• % ‘10%’

26

• % ‘10%’

• _ ‘USA_Canada’



• ’ ‘Baby’s World’

Search for all company names having apostrophe s in the

27

Search for all company names having apostrophe s in the name?

Use double apostrophe

SELECT *

FROM Company

WHERE cname LIKE ‘%’’s%’



• % ‘10%’

Search for all interest rates having percent at the end?

28

Search for all interest rates having percent at the end?

Use ESCAPE characters

SELECT *

FROM Bank

WHERE interestRates LIKE ‘%\%’ ESCAPE ‘\’



• ‘_’ ‘USA_Canada’

Search for all country names having underscore inside?

29

Search for all country names having underscore inside?

Use ESCAPE characters

SELECT *

FROM Company

WHERE country LIKE ‘%\_%’ ESCAPE ‘\’


LIKE does not pad with blank before matching

SELECT pname, price, manufacturerFROM ProductWHERE category =‘Household’

CSE 303: Ashikur Rahman 30

WHERE category =‘Household’

SELECT pname, price, manufacturerFROM ProductWHERE category LIKE ‘Household’

Not equivalent

The NOT LIKE operatorPName Price Category Manufacturer





3131

SELECT *FROM ProductsWHERE manufacturer NOT LIKE ‘%mo%’









Product

Combining Predicates

3232



Show all household products having prices more than $100








Product

Show all manufacturer that make photography or household items

333333


SELECT DISTINCT makerFROM ProductWHERE category =‘Photography’OR category =‘Household’

Manufacturer

Canon

HitachiCSE 303: Ashikur Rahman







Product

Show all manufacturer that make both photography and household items

WRONG!

343434


SELECT DISTINCT makerFROM ProductWHERE category =‘Photography’AND category =‘Household’



Combining PredicatesPName Price Category Manufacturer





SELECT *

Product

353535

SELECT *FROM ProductWHERE pname LIKE ‘%Giz%’OR category LIKE ‘%hold’AND price > 100

Pname Price Category Manufacturer



AND has higher precedence over OR

CSE 303: Ashikur Rahman0

Combining PredicatesPName Price Category Manufacturer





SELECT *

Product

363636

SELECT *FROM ProductWHERE (pname LIKE ‘%Giz%’OR category LIKE ‘%hold’)AND price > 100




Ordering the Results

SELECT pname, price, manufacturer






Default order is AscendingUse DESC for descending

37

SELECT pname, price, manufacturerFROM ProductWHERE price > 50ORDER BY pname





ORDER BY: Sorting the Results

SELECT PName, Price, ManufacturerFROM ProductWHERE Category=‘gizmo’ AND Price > 50ORDER BY Price, PName

CSE 303: Ashikur Rahman 38

ORDER BY Price, PName

Ties are broken by the second attribute on the ORDER BY list, etc.

Ties are broken by the second attribute on the ORDER BY list, etc.

Ordering is ascending, unless you specify the DESC keyword.

Ordering is ascending, unless you specify the DESC keyword.

IN operator

artist album tracks company year

U2 The Unforgettable 10 Island 1984

U2 Rattle and Hum 17 Island 1988

U2 Achtung Boys 12 Island 1991

Underworld Second Toughest 8 Junior 1996

CDCollection

Find all albums launched in 1984 or 1996.

3939

SELECT albumFROM CDCollectionWHERE year IN (1984, 1996)




SELECT albumFROM CDCollectionWHERE year =1984OR year =1996 CSE 303: Ashikur Rahman

NOT IN operatorartist album tracks company year





CDCollection

4040

SELECT *FROM CDCollectionWHERE year NOT IN (1984, 1996)




SELECT *FROM CDCollectionWHERE year < > 1984AND year < > 1996


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