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Copyright © 2004 Pearson Education, Inc.

Chapter 8SQL-99: Schema

Definition, BasicConstraints, and Queries

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Slide 8-2Elmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition

Copyright © 2004 Rae! Elasri and Sha"ant #a$athe

Data Definition, Constraints,

and Schema Changes%sed to CRE&'E, (R)P, and &*'ER the

descriptions o+ the tales relations o+ a

dataaseSynta/

CRE&'E (&'&1&SE dataasenae 3

CRE&'E '&1*E talenae

colunnae datatype,

colunnae2 datatype, .......

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CREATE TABLE

Speci+ies a ne6 ase relation y gi$ing it a nae,and speci+ying each o+ its attriutes and their datatypes I#'E7ER, *)&', (ECI9&*i,:,C;&Rn,

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CREATE TABLE: Data Type

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Slide 8-=Elmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


CREATE TABLE

In S>*2, can use the CRE&'E '&1*E coand +orspeci+ying the priary "ey attriutes, secondary "eys, and

re+erential integrity constraints +oreign "eys. ?ey attriutes can e speci+ied $ia the PRI9&R@ ?E@ and

%#I>%E phrases

CREATE TABLE DEPT

( DNAME VARCHAR(10) NOT NULL,DNUMBER INTEGER NOT NULL,

MGRSSN CHAR(9),MGRSTARTDATE CHAR(9),PRIMARY KEY (DNUMBER),UNIQUE (DNAME),FOREIGN KEY (MGRSSN) REFERENCES EMP );

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Slide 8-AElmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


DROP TABLE

%sed to reo$e a relation ase tale and

its definition

'he relation can no longer e used in

Bueries, updates, or any other coands

since its description no longer e/ists

E/aple

DROP TABLE DEPENDENT;

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7/76Slide 8-Elmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


ALTER TABLE

%sed to add an attriute to one o+ the ase relations

'he ne6 attriute 6ill ha$e #%**s in all the tuples o+ the

relation right a+ter the coand is e/ecuted3 hence, the

#)' #%** constraint is not allowed +or such an attriute

E/aple

ALTER TABLE EMPLOYEE ADD JOB

VARCHAR(1);

'he dataase users ust still enter a $alue +or the ne6

attriute D)1 +or each E9P*)@EE tuple. 'his can e

done using the %P(&'E coand.

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8/76Slide 8-8Elmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


Featres Added in S!L" and

S!L#$$CREATE SCHEMAREFERENTIAL INTEGRITY

OPTIONS

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CREATE SC%E&A

the stateent can include all the eleentsFde+initions. G Schea eleents include tales, constraints, $ie6s,

doains, and other constructs such as authori!ation

grants&lternati$ely, the schea can e assigned a

nae and authori!ation identi+ier. 'he eleentscan e de+ined later.

EH schea o6ned y the user 6ith DS9I'; G CRE&'E SC;E9& copany &%';)RI&'I)#

DS9I';3

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Attri'tes Constraints

Speci+y constraint on attriute

G (#%91ER I#' #)' #%** CHECK

(#%91ER J 0 ( (#%91ER K 2

&lternati$ely

G CREATE DOMAIN (#%9 &S I#'E7ER

C;EC? (#%9J0 ( (#%9K2

G (#%91ER (#%9

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Additiona( Data Types in

S!L" and S!L#$$;as (&'E, 'I9E, and 'I9ES'&9P data typesDATE!

G 9ade up o+ year-onth-day in the +orat yyyy--dd

TIME! G 9ade up o+ hourinutesecond in the +orat hhss

TIME(")! G 9ade up o+ hourinutesecond plus i additional digits

speci+ying +ractions o+ a second G +orat is hhssii...i

TIMESTAMP! G ;as oth (&'E and 'I9E coponents

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Additiona( Data Types in

S!L" and S!L#$$ )cont*+INTERVAL!

G Speci+ies a relati$e $alue rather than an asolute $alue

G Can e (&@L'I9E inter$als or @E&RL9)#';

inter$als G Can e positi$e or negati$e 6hen added to or

sutracted +ro an asolute $alue, the result is anasolute $alue

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Referentia( ntegrity )R+

RI constraints can e $iolated 6hen tuples

are inserted or deleted, or 6hen a +oreign

"ey or priary "ey is odi+ied

(e+ault action

G Re:ect the update operation that 6ill cause the

$iolation

R#$#%#&'" '%"**#%#+ '"-&.

G SE' #%**, SE' (E&%*', C&SC&(E

G Mhen )# (E*E'E or )# %P(&'E

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15/76Slide 8-=Elmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


REFERE-TAL -TE.RT/OPTO-S )contined+

CREATE TABLE EMP( ENAME VARCHAR(/0) NOT NULL,

ESSN CHAR(9) %"%2 3#2,

BDATE DATE,DNO INTEGER DEFAULT 1 4#3 (+&-50 &+ +&-69)

SUPERSSN CHAR(9),7 PRIMARY KEY (ESSN),FOREIGN KEY (DNO) REFERENCES DEPT

ON DELETE SET DEFAULT ON UPDATE CASCADE,FOREIGN KEY (SUPERSSN) REFERENCES EMP

ON DELETE SET NULL ON UPDATE CASCADE );

I+ the tuples +or a super$ising eployee is deleted, the $alue o+

S%PERSS# is set to #%**.

I+ SS# is updated, the ne6 $alue is cascaded to S%PERSS#.

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16/76Slide 8-AElmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


Retrie0a( !eries in S!L

S>* has one asic stateent +or retrie$ing in+oration

+ro a dataase3 the SE*EC' stateent

'his is not the same as the SE*EC' operation o+ the

relational algera

Iportant distinction et6een S>* and the +oral

relational odel3 S>* allo6s a tale relation to ha$e t6o

or ore tuples that are identical in all their attriute $alues

;ence, an S>* relation tale is a multi-set soeties

called a ag o+ tuples3 it is not a set o+ tuplesS>* relations can e constrained to e sets y speci+ying

PRI9&R@ ?E@ or %#I>%E attriutes, or y using the(IS'I#C' option in a Buery

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Retrie0a( !eries in S!L

)cont*+1asic +or o+ the S>* SE*EC' stateent is called amapping or a SELECT-FROM-WHERE blo!

SELECT Kattriute listJ

FROM Ktale listJ

8HERE KconditionJ

G Kattriute listJ is a list o+ attriute naes 6hose $alues are to eretrie$ed y the Buery

G Ktale listJ is a list o+ the relation naes reBuired to process theBuery

G KconditionJ is a conditional 1oolean e/pression that identi+iesthe tuples to e retrie$ed y the Buery

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Re(ationa( Data'ase Schema##Figre 1*1 httpLL6e.ntnu.edu.t6LNsatsengL

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Pop(ated

Data'ase##Fig*1*2

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Elmasri and Navathe, undamentals of Data!ase S"stems, Fourth EditionCopyright © 2004 Rae! Elasri and Sha"ant #a$athe

Simp(e S!L !eries

1asic S>* Bueries correspond to using the SE*EC', PR)DEC', andD)I# operations o+ the relational algera

&ll suseBuent e/aples use the C)9P@ dataase

E/aple o+ a siple Buery on one relation

>uery 0 Retrie$e the irthdate and address o+ the eployee 6hose

nae is ODohn 1. SithO.

Q0! SELECT BDATE, ADDRESSFROM EMPLOYEE8HERE FNAME:J-4&: AND MINIT:B

AND LNAME:S"'4

G Siilar to a SE*EC'-PR)DEC' pair o+ relational algera operations3 theSE*EC'-clause speci+ies the p"o#etion att"ibutes and the M;ERE-clausespeci+ies the seletion ondition

G ;o6e$er, the result o+ the Buery ma$ ontain duplicate tuples

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Simp(e S!L !eries )cont*+

>uery Retrie$e the nae and address o+ all eployees 6ho 6or"+or the OResearchO departent.

Q1! SELECT FNAME, LNAME, ADDRESSFROM EMPLOYEE, DEPARTMENT

8HERE DNAME:R#.#%4: ANDDNUMBERDNO

G Siilar to a SE*EC'-PR)DEC'-D)I# seBuence o+ relationalalgera operations

G (#&9EOResearchO is a seletion ondition corresponds to aSE*EC' operation in relational algera

G (#%91ER(#) is a #oin ondition corresponds to a D)I#operation in relational algera

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Simp(e S!L !eries )cont*+

>uery 2 or e$ery pro:ect located in OSta++ordO, list the pro:ect nuer, thecontrolling departent nuer, and the departent anagerOs last nae,address, and irthdate.

Q! SELECT PNUMBER, DNUM, LNAME, BDATE, ADDRESS

FROM PROJECT, DEPARTMENT, EMPLOYEE8HERE DNUMDNUMBER AND MGRSSNSSNAND PLOCATION:S'$$-%+:

G In >2, there are two :oin conditions G 'he :oin condition (#%9(#%91ER relates a pro:ect to its controlling

departent

G 'he :oin condition 97RSS#SS# relates the controlling departent tothe eployee 6ho anages that departent

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A(iases, 3 and DST-CT,

Empty 4%ERE#c(ase In S>*, 6e can use the sae nae +or t6o or oreattriutes as long as the attriutes are in diffe"ent "elations

& Buery that re+ers to t6o or ore attriutes 6ith the sae

nae ust %ualif$ the attriute nae 6ith the relationnae y p"efi&ing the relation nae to the attriute nae

E/aple

E9P*)@EE.*#&9E, (EP&R'9E#'.(#&9E

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ALASES

Soe Bueries need to re+er to the sae relation t6ice

In this case, aliases are gi$en to the relation nae

>uery 8 or each eployee, retrie$e the eployeeOs nae, and the naeo+ his or her iediate super$isor.

Q

FROM EMPLOYEE E S8HERE E=SUPERSSNS=SSN

G In >8, the alternate relation naes E and S are called aliases or tuple'a"iables +or the E9P*)@EE relation

G Me can thin" o+ E and S as t6o diffe"ent opies o+ E9P*)@EE3 Erepresents eployees in role o+ supe"'isees and S representseployees in role o+ supe"'iso"s

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Slide 8-2=Elmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


ALASES )cont*+

G &liasing can also e used in any S>* Buery +or con$enienceCan also use the &S "ey6ord to speci+y aliases

Q

FROM EMPLOYEE AS E, EMPLOYEE AS S8HERE E=SUPERSSNS=SSN

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Slide 8-2AElmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


5-SPECFED

4%ERE#c(ase& missing WHERE-lause indicates no condition3 hence,all tuples o+ the relations in the R)9-clause are selected

'his is eBui$alent to the condition M;ERE 'R%E

>uery Retrie$e the SS# $alues +or all eployees.

Q9! SELECT SSN

FROM EMPLOYEE

I+ ore than one relation is speci+ied in the R)9-clause

and there is &- >-"& -&+"'"-&, '4#& '4# CARTESIAN

PRODUCT -$ '?#. ". .##'#+

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5-SPECFED

4%ERE#c(ase )cont*+E/aple

Q10! SELECT SSN, DNAME

FROM EMPLOYEE, DEPARTMENT

G It is e/treely iportant not to o$erloo" speci+ying any selection and :oin conditions in the M;ERE-clause3 other6ise, incorrect and $erylarge relations ay result

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Simp(e E6amp(escreate dataase coursesstudents3

use coursesstudents3

Q 'ale de+initioncreate tale courses

cid int0 #)' #%** autoincreent,

cnae $archar50 #)' #%**,

credit tinyint2 #)' #%**,

croo $archar0,

priary "ey cid3

create tale students

sid int0 unsigned #)' #%**autoincreent,

snae $archar50 #)' #%** de+ault OO,

syear tinyint2 unsigned,

priary "ey sid3

create tale selected

cid int0 unsigned,

sid int0 unsigned

3

Q (atainsert into courses $alues , O(19SO, 5, O50O3

insert into courses $alues 2, O)SO, 5, O40AO3insert into courses $alues 5, O&lgorithO, 5, O50O3

insert into students $alues , OSaO, 43

insert into students $alues 2, ODoeO, 53

insert into students $alues 5, O9aryO, 53

insert into students $alues 4, ODohnO, 53

insert into selected $alues , 3



insert into selected $alues 2, 3






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7oin Operations

select selected.cid, selected.sid, snae+ro selected, students

@4#%# .##'#+=."+ .'?+#&'.=."+;

-------------------

cid sid snae

------------------- 2 Doe

4 Dohn

Sa

2 2 Doe

2 5 9ary

2 4 Dohn

2 Sa

5 4 Dohn

5 2 Doe

-------------------

select T +ro

students3

-------------------

sid snae syear

-------------------

Sa 4

2 Doe 5

5 9ary 5 4 Dohn 5

-------------------

select T +ro selected3

------------ cid sid

------------

2

4

2

2 5

2 4

2 2

5 2

5 4 ------------

I+ oitted,

5A ro6s6ill result.

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5SE OF 3

'o retrie$e all the attriute $alues o+ the selected tuples, a T is

used, 6hich stands +or all the att"ibutes

E/aples

Q1C! SELECT

FROM EMPLOYEE

8HERE DNO

Q1D! SELECT FROM EMPLOYEE, DEPARTMENT

8HERE DNAME:R#.#%4: AND

DNODNUMBER

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5SE OF DST-CT

S>* does not treat a relation as a set3 dupliate tuples an

appea"

'o eliinate duplicate tuples in a Buery result, the

"ey6ord DISTINCT is used

or e/aple, the result o+ > ay ha$e duplicate

S&*&R@ $alues 6hereas >& does not ha$e any

duplicate $alues

Q11! SELECT SALARYFROM EMPLOYEE

Q11A! SELECT DISTINCT SALARY

FROM EMPLOYEE

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Slide 8-55Elmasri and Navathe, undamentals of Data!ase S"stems,

Fourth Edition


SET OPERATO-S )cont*+

>uery 4 9a"e a list o+ all pro:ect nuers +or pro:ects that in$ol$e aneployee 6hose last nae is OSithO as a 6or"er or as a anager o+

the departent that controls the pro:ect.

Q! (SELECT PNAME

FROM PROJECT, DEPARTMENT, EMPLOYEE8HERE DNUMDNUMBER AND MGRSSNSSN

AND LNAME:S"'4:)

UNION (SELECT PNAME

FROM PROJECT, 8ORKSON, EMPLOYEE

8HERE PNUMBERPNO AND ESSNSSN ANDLNAME:S"'4:)

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Fourth Edition


-EST-. OF !5ERES

& coplete SE*EC' Buery, called a nested %ue"$ , can e speci+ied6ithin the M;ERE-clause o+ another Buery, called the oute" %ue"$

9any o+ the pre$ious Bueries can e speci+ied in an alternati$e +or

using nesting

>uery Retrie$e the nae and address o+ all eployees 6ho 6or"

+or the OResearchO departent.

Q1! SELECT FNAME, LNAME, ADDRESS

FROM EMPLOYEE

8HERE DNO IN (SELECT DNUMBER

FROM DEPARTMENT8HERE DNAME:R#.#%4: )

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Slide 8-5=Elmasri and Navathe, undamentals of Data!ase S"stems,

Fourth Edition


-EST-. OF !5ERES

)cont*+

'he nested Buery selects the nuer o+ the OResearchO departent

'he outer Buery select an E9P*)@EE tuple i+ its (#) $alue is in theresult o+ either nested Buery

'he coparison operator IN copares a $alue $ 6ith a set or ulti-seto+ $alues

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Fourth Edition


CORRELATED -ESTED

!5ERES )cont*+ G In >2, the nested Buery has a di++erent result fo" eah tuple in the outer

Buery

G & Buery 6ritten 6ith nested SE*EC'... R)9... M;ERE... loc"s andusing the or I# coparison operators can always e e/pressed as asingle loc" Buery. or e/aple, >2 ay e 6ritten as in >2&

Q1A! SELECT E=FNAME, E=LNAMEFROM EMPLOYEE E, DEPENDENT D8HERE E=SSND=ESSN AND

E=FNAMED=DEPENDENTNAME

G 'he original S>* as speci+ied +or S@S'E9 R also had a CONTAINS coparison operator, 6hich is used in con:unction 6ith nested correlatedBueries

G 'his operator 6as dropped +ro the language, possily ecause o+ thedi++iculty in ipleenting it e++iciently

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Fourth Edition


CORRELATED -ESTED

!5ERES )cont*+

G 9ost ipleentations o+ S>* do not ha$e this operator

G 'he C)#'&I#S operator copares t6o sets of 'alues , and returns 'R%Ei+ one set contains all $alues in the other set reiniscent o+ the di'ision operation o+ algera.

>uery 5 Retrie$e the nae o+ each eployee 6ho 6or"s onall the pro:ectscontrolled y departent nuer =.

Q/! SELECT FNAME, LNAMEFROM EMPLOYEE8HERE ( (SELECT PNO

FROM 8ORKSON

8HERE SSNESSN) CONTAINS (SELECT PNUMBER FROM PROJECT 8HERE DNUM) )

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Fourth Edition


CORRELATED -ESTED

!5ERES )cont*+

G In >5, the second nested Buery, 6hich is not correlated6ith the outer Buery, retrie$es the pro:ect nuers o+ all

pro:ects controlled y departent =

G 'he +irst nested Buery, 6hich is correlated, retrie$es the

pro:ect nuers on 6hich the eployee 6or"s, 6hich isdi++erent fo" eah emplo$ee tuple ecause o+ thecorrelation

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Fourth Edition


T%E E8STS F5-CTO-

EHIS'S is used to chec" 6hether the result

o+ a correlated nested Buery is epty

contains no tuples or not

Me can +orulate >uery 2 in an

alternati$e +or that uses EHIS'S as >21

elo6

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Fourth Edition


E8PLCT SETS

It is also possile to use an #""' (#&?#%'#+) .#' -$

?#. in the M;ERE-clause rather than a nested Buery

>uery 5 Retrie$e the social security nuers o+ all

eployees 6ho 6or" on pro:ect nuer , 2, or 5.

Q1/! SELECT DISTINCT ESSN

FROM 8ORKSON

8HERE PNO IN (1, , /)

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Fourth Edition


-5LLS - S!L !5ERES

S>* allo6s Bueries that chec" i+ a $alue is #%** issingor unde+ined or not applicale

S>* uses IS or IS NOT to copare #%**s ecause it

considers each #%** $alue distinct +ro other #%**

$alues, so eBuality coparison is not appropriate .>uery 4 Retrie$e the naes o+ all eployees 6ho do not

ha$e super$isors.

Q1! SELECT FNAME, LNAME

FROM EMPLOYEE8HERE SUPERSSN IS NULL

#ote I+ a :oin condition is speci+ied, tuples 6ith #%**

$alues +or the :oin attriutes are not included in the result

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Slide 8-4=Elmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


7oined Re(ations Featre

in S!L"Can speci+y a U:oined relationU in the R)9-clause

*oo"s li"e any other relation ut is the result o+ a :oin

&llo6s the user to speci+y di++erent types o+ :oins regular

UthetaU D)I#, #&'%R&* D)I#, *E' )%'ER D)I#,RI7;' )%'ER D)I#, CR)SS D)I#, etc

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Slide 8-4AElmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition



in S!L" )cont*+ E/aples

Q

can e 6ritten as #ote there is one ro6 in di++erence

Q

ON E=SUPERSSNS=SSN)

Q1! SELECT FNAME, LNAME, ADDRESSFROM EMPLOYEE, DEPARTMENT8HERE DNAME:R#.#%4: AND DNUMBERDNO

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in S!L" )cont*+ could e 6ritten as

Q1! SELECT FNAME, LNAME, ADDRESSFROM (EMPLOYEE JOIN DEPARTMENT

ON DNUMBERDNO)8HERE DNAME:R#.#%4

or as

Q1! SELECT FNAME, LNAME, ADDRESSFROM (EMPLOYEE NATURAL JOIN DEPARTMENT

AS DEPT(DNAME, DNO, MSSN, MSDATE)8HERE DNAME:R#.#%4

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in S!L" )cont*+&nother E/aple3

G >2 could e 6ritten as +ollo6s3 this illustrates ultiple :oins in the :oined tales

Q! SELECT PNUMBER, DNUM,LNAME, BDATE,ADDRESS

FROM ((PROJECT JOINDEPARTMENT ON

DNUMDNUMBER) JOINEMPLOYEE ONMGRSSNSSN)

8HERE PLOCATION:S'$$-%+

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A..RE.ATE F5-CTO-S

Include COUNT, SUM, MA, MIN, and AVG

>uery = ind the a/iu salary, the iniu salary, and

the a$erage salary aong all eployees.

Q1! SELECT MA(SALARY),

MIN(SALARY), AVG(SALARY)

FROM EMPLOYEE

G Soe S>* ipleentations ma$ not allow mo"e than one funtion in the SE*EC'-clause

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Slide 8-=0Elmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


A..RE.ATE F5-CTO-S

)cont*+>uery A ind the a/iu salary, the iniu salary,

and the a$erage salary aong eployees 6ho 6or" +or theOResearchO departent.

Q1! SELECT MA(SALARY), MIN(SALARY),AVG(SALARY)

FROM EMPLOYEE, DEPARTMENT8HERE DNODNUMBER AND

DNAME:R#.#%4:

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A..RE.ATE F5-CTO-S

)cont*+>ueries and 8 Retrie$e the total nuer o+ eployees

in the copany >, and the nuer o+ eployees in theOResearchO departent >8.

Q1! SELECT COUNT ()FROM EMPLOYEE

Q1

DEPARTMENT8HERE DNODNUMBER AND

DNAME:R#.#%4

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Slide 8-=2Elmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


.RO5P-.

In any cases, 6e 6ant to apply the aggregate+unctions to subg"oups of tuples in a "elation

Each sugroup o+ tuples consists o+ the set o+tuples that ha$e the same 'alue +or the g"oupingatt"ibute(s)

'he +unction is applied to each sugroupindependently

S>* has a GROUP BY-clause +or speci+ying thegrouping attriutes, 6hich must also appea" in theSELECT-lause

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Slide 8-==Elmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


T%E %A9-.#CLA5SE

Soeties 6e 6ant to retrie$e the $alues

o+ these +unctions +or only those g"oups that

satisf$ e"tain onditions

'he ;&

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S S . CO SO

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S5BSTR-. CO&PARSO-

'he LIKE coparison operator is used to

copare partial strings

'6o reser$ed characters are used OVO or OTO

in soe ipleentations replaces anaritrary nuer o+ characters, and OO

replaces a single aritrary character

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S5BSTR-. CO&PARSO-

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S5BSTR-. CO&PARSO-

)cont*+>uery 2A Retrie$e all eployees 6ho 6ere orn during the

=0s. ;ere, O=O ust e the 8th character o+ the stringaccording to our +orat +or date, so the 1(&'E $alue isO=O, 6ith each underscore as a place holder +or a

single aritrary character.

Q! SELECT FNAME, LNAMEFROM EMPLOYEE8HERE BDATE LIKE :

'he *I?E operator allo6s us to get around the +act that each$alue is considered atoic and indi$isile3 hence, in S>*,character string attriute $alues are not atoic

ART%&ETC OPERATO-S

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Slide 8-A0Elmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


ART%&ETC OPERATO-S

'he standard arithetic operators OO, O-O. OTO, and OLO +or addition,

sutraction, ultiplication, and di$ision, respecti$ely can e

applied to nueric $alues in an S>* Buery result

>uery 2 Sho6 the e++ect o+ gi$ing all eployees 6ho 6or"

on the OProductHO pro:ect a 0V raise.

Q!SELECT FNAME, LNAME, 1=1SALARY

FROM EMPLOYEE, 8ORKSON, PROJECT

8HERE SSNESSN AND PNOPNUMBER AND

PNAME:P%-+?'

ORDER B/

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ORDER B/

'he ORDER BY clause is used to sort the tuples in aBuery result ased on the $alues o+ soe attriutes

>uery 28 Retrie$e a list o+ eployees and the

pro:ects each 6or"s in, ordered y the eployeeOsdepartent, and 6ithin each departent orderedalphaetically y eployee last nae.

Q

FROM DEPARTMENT, EMPLOYEE,8ORKSON, PROJECT

8HERE DNUMBERDNO AND SSNESSNAND PNOPNUMBER ORDER BY DNAME, LNAME

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S f S!L ! i

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Smmary of S!L !eries

& Buery in S>* can consist o+ up to si/ clauses, ut onlythe +irst t6o, SE*EC' and R)9, are andatory. 'he

clauses are speci+ied in the +ollo6ing order

SELECT 6''%"?'# ".'5FROM 6'# ".'5

8HERE 6-&+"'"-&5

GROUP BY 6*%-?"&* ''%"?'#(.)5

HAVING 6*%-? -&+"'"-&5

ORDER BY 6''%"?'# ".'5

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S if i 5 d t i S!L

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Slide 8-A=Elmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


Specifying 5pdates in S!L

'here are three S>* coands to odi+ythe dataase3 I#SER', (E*E'E, and

%P(&'E

-SERT

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Slide 8-AAElmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


-SERT

In its siplest +or, it is used to add one orore tuples to a relation

&ttriute $alues should e listed in the

sae order as the attriutes 6ere speci+iedin the CRE&'E '&1*E coand

-SERT ) t +

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-SERT )cont*+

E/aple

U1! INSERT INTO EMPLOYEEVALUES (:R"4%+:,:K:,:M%"&":, :/9

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-SERT )cont*+

Iportant #ote )nly the constraints speci+ied inthe ((* coands are autoatically en+orced ythe (19S 6hen updates are applied to thedataase

&nother $ariation o+ I#SER' allo6s insertion o+multiple tuples resulting +ro a Buery into arelation

-SERT ) t +

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-SERT )cont*+

G E/aple Suppose 6e 6ant to create a teporary tale that has the nae,nuer o+ eployees, and total salaries +or each departent. & tale(EP'SI#) is created y %5&, and is loaded 6ith the suaryin+oration retrie$ed +ro the dataase y the Buery in %51.

U/A! CREATE TABLE DEPTSINFO(DEPTNAME VARCHAR(10), NOOFEMPS INTEGER, TOTALSAL INTEGER);

U/B! INSERT INTO DEPTSINFO (DEPTNAME,NOOFEMPS, TOTALSAL)

SELECT DNAME, COUNT (), SUM (SALARY)

FROM DEPARTMENT, EMPLOYEE8HERE DNUMBERDNOGROUP BY DNAME ;

-SERT )cont +

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-SERT )cont*+

#ote 'he (EP'SI#) tale ay not e up-to-date i+ 6echange the tuples in either the (EP&R'9E#' or theE9P*)@EE relations afte" issuing %51. Me ha$e tocreate a $ie6 see later to "eep such a tale up to date.

DELETE

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Slide 8-Elmasri and Navathe, undamentals of Data!ase S"stems, Fourth Edition


DELETE

Reo$es tuples +ro a relation Includes a M;ERE-clause to select the tuples to e deleted

'uples are deleted +ro only one table at a tie unlessC&SC&(E is speci+ied on a re+erential integrity

constraint& issing M;ERE-clause speci+ies that all tuples in the

relation are to e deleted3 the tale then ecoes an eptytale

'he nuer o+ tuples deleted depends on the nuer o+tuples in the relation that satis+y the M;ERE-clause

Re+erential integrity should e en+orced

DELETE )cont +

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DELETE )cont*+

E/aplesUA! DELETE FROM EMPLOYEE

8HERE LNAME:B%-@&

UB! DELETE FROM EMPLOYEE

8HERE SSN:1/

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5PDATE

%sed to odi+y attriute $alues o+ one or oreselected tuples

& M;ERE-clause selects the tuples to e

odi+ied&n additional SE'-clause speci+ies the attriutes

to e odi+ied and their ne6 $alues

Each coand odi+ies tuples in the same

"elation

Re+erential integrity should e en+orced

5PDATE )cont +

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5PDATE )cont*+

E/aple Change the location and controlling departentnuer o+ pro:ect nuer 0 to O1ellaireO and =,respecti$ely.

U! UPDATE PROJECTSET PLOCATION :B#"%#:, DNUM 8HERE PNUMBER10

5PDATE )cont +

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5PDATE )cont*+

E/aple 7i$e all eployees in the OResearchO departent a 0V raisein salary.

U! UPDATE EMPLOYEESET SALARY SALARY 1=1

8HERE DNO IN (SELECT DNUMBER FROM DEPARTMENT 8HERE DNAME:R#.#%4:)

In this reBuest, the odi+ied S&*&R@ $alue depends on the originalS&*&R@ $alue in each tuple

'he re+erence to the S&*&R@ attriute on the right o+ re+ers to the oldS&*&R@ $alue e+ore odi+ication

'he re+erence to the S&*&R@ attriute on the le+t o+ re+ers to the ne6S&*&R@ $alue a+ter odi+ication

%ome 4or

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%ome 4or

8.hand in 9yS>*-e/ecutale coands

8.0 hand in 9yS>*-e/ecutale coands

8. hand in 9yS>*-e/ecutale coands

8.4 hand in 9yS>*-e/ecutale coands

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ENCh08