SQL

CHAPTER 1

RDBMS Concepts

Database A database is the place of storage of the data in the form of tables Data means information which is very useful. A database is also collection of 1 or more tables. Table – Table – a table is a collection of rows and columns.

CELL CELL

Columns A cell is an intersection of a row and a column A column is also called as a eld / attribute A record is also called as a row / tuple. A table is also called as an entity / relation. Note :If we inst instal alll any any of the the data databa base se relat elated ed soft softwa warre(s e(s – we can can crea create te our our own own • database! we can create our own tables and we can store the data inside it. "hen we install any database s/w(s – a part of hard dis# will be designated / • reserved to perform database related activities A databa database se can also also contai contain n other other datab databas ase e ob$ect ob$ects s li#e li#e views views!! inde% inde%es! es! store stored d • procedures! functions! triggers etc! apart from tables.

&ome of the database software(s we have are! 'racle! &) &erver! D*+! &ybase! Informi%! ,y&)! ,& – Access! -o%base! -o%ro Among the above database software – some of them are D*,& and some of them are D*,&  0he s/w which is widely used today is 'racle. 0he dierent versions of 'racle starting from the earliest to the latest are – 'racle +! 'racle 2! 'racle 3! 'racle 4! 'racle 5! 'racle 6! 17age

'racle 8i! 'racle 9i! 'racle 1:g! and the latest to hit the mar#et is 'racle 11g. here ;i< stands for Internet and ;g< stands for =rid / =rid computing. RELATIONSHIPS A relationship is the association between any two tables which preserves data integrity. Relationsips

Dept No$

Dept Name

Emp No$

Emp Name

Dept No$

Sala!%

1:

Accounting

1:1

A

1:

+::::

+:

esearch

1:+

*

1:

2:::: :

2:

&ales

1:2

>

+:

2::::

Maste! " Pa!ent #

Detail " Cil& #

elationship helps to prevent the incorrect data in the child tables 'nce the relationship is created! one table becomes master (or parent and the other one becomes the child ( or detail . "hatever we insert into the child should be present in the master! else the record will be re$ected from the child.  0he master table table contains the master data data which will will not change change fre?uently fre?uently..  0he child table table contains the the transactional transactional data which which will change change ?uite often. often. DBMS @ RDBMS DBMS – DBMS – stands for Database ,anagement &ystem D*,& is a database s/w which allows us to store the data in the form of tables. RDBMS – RDBMS – stands for elational D*,& D*,& D*,& is also also a databa database se s/w s/w which which has facili facility ty to handl handle e more more data data volu volume! me! good good performance! enhanced security features etc when compared against D*,&. Any D*,& to ?ualify as a D*,& should support the >odd rules / >odd laws E' for E' for D*,& – -o%ro! -o%*ase! Dbase E' for E' for D*,& – 'racle! &ybase! D*+! 0eradata! &) &erver! ,y&) CONSTRAINTS A constraint is a condition which restricts the invalid data in the table. A constraint can be provided for a column of a table.

T%pes o( Const!aints  '0 B)) +7age

   

BIBC rimary ey -oreign ey >hec#

N)LL → → → → →

B)) is nothing! it is neither Eero nor blan# space It will not occupy any space in the memory  0wo  0wo B))& are are never same in in 'racle. B)) represents un#nown value Any arithmet arithmetic ic opera operatio tion n we perfor perform m on B)) B)) will will resu result lt in B B)) )) itself itself.. *o! e'+ 1::::: F B)) G B)) H 1:::::  B)) G B))

NOT N)LL J '0 B)) will ensure atleast some value should be present in a column )NI,)E → It will not allow any duplicates in a column → BIBC column can ta#e multiple B)) (s P!ima!% e% N)LL and )NI,)E → It is the combination of NOT N)LL and → 'nly one  is allowed in a table →  identies a record uni?uely in a table → >reation of  is not mandatory! but it is highly recommended to create *o!ei.n e% → - creates relationship between any two tables → - is also called as referential integrity constraints → - is created on the child table → - can ta#e both B)) and duplicate values  0o create -! the master table should have  dened on the common column of the →  0o master table → "e can have more than 1 - in a given table CHEC  It is used to provide additional validations as per the customer re?uirements. E' - 1 sal K : + empnum should start with 1 2 commission should be between 1::: @ 4:::

Cec/  "sal 0 1#

27age

P

NN

P

NN

*

NN

)ni2u e

)ni2u e

Dept No$

Dept name

Emp No$

Emp Name

Dept No$

Sala!%

P No$

Email

1:

Accountin g

1:1

A

1:

+:::: :

++++

aLgm ail

+:

esearch

1:+

*

1:

2::::

J

J

2:

&ales

1:2

>

+:

3:::: :

2222

J

RELATIONSHIP

N)LL

CHAPTER 2

S,L 3 St!uctu!e& ,ue!% Lan.ua.e 37age

&) – &tructured uery )anguage &) – it is a language to tal# to the database / to access the database &) – it is a language! whereas &) server is a database.  0o  0o wor# on &) &) ! a D* software software (D*,& (D*,& is re?uired. re?uired. &) is not case sensitive )se!name J &cott Pass4o!& – Pass4o!& – 0iger T!oublesootin. O!acle Error 1  0he account account is loc#ed loc#ed Steps to rectify the error )ogin as username – ;system< @ password – ;manager< or ;password – ;tiger< • &) K show user H • Bser is M&N&0C,O

&) K alter user scott account unloc# H Bser altered &) K e%it H Error 2  0& P protocol protocol adapter error error How to troubleshoot this >ause is Moracle service has not startedO

Qow to go here! &ettings – >ontrol anel – Administrative 0ools – &ervices &ort the list  0here is an M'racle M'racle &ervice &ervice '>) '>)O @ Mstart the serviceO serviceO

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 0his ?uery ?uery gives the list list of tables. tables.  J selects all

 0his ?uery ?uery gives the description description of of the table MdepartmentO. MdepartmentO.  0he description description of the table table has column names+ const!aints+ &atat%pes

 0his ?uery ?uery gives the description description of of the table MdepartmentO MdepartmentO

 0he above ?uery ?uery gives the the description description of the MemployeeO MemployeeO table. *ut we see that all the the data is in dierent lines which ma#es it very diRcult to analyse. &o we use the following command to see the data in a more orderly fashion!

57age

 0he 5set linesi6e7 command linesi6e7 command helps in increasing the line siEe ! thus the data is arranged in a orderly fashion.

 0he above command command 5set pa.esi6e 817 increases 817  increases the page siEe! thus accommodating more number of rows in a single page.

67age

 0he above ?uery ?uery gives the the value of only only these 2 columns columns from from the table MemployeeO. MemployeeO.

94e!e clause 94e!e clause is used to restrict the number of records displayed. It gives only the records of the specied condition.

Any string data should be enclosed within sin.le 2uotes  2uotes  ( ; ;  and the the same same beco becomes mes case sensiti;e. sensiti;e. Assi.nment <# List te emplo%ees in &ept 81

87age

8# List te emplo%ees ea!nin. mo!e tan Rs 8=11$

># Displa% all salesmen

CHAPTER 3

OPERATORS 97age

'perators are classied into! A!itmetic Ope!ato!s ( Ope!ato!s ( F! J !  ! /  • Relational Ope!ato!s ( Ope!ato!s ( K ! S ! KG ! SG ! G ! S K o! TG o! TG J not e?uals to  • Lo.ical Ope!ato!s ( Ope!ato!s ( '0! AD! '  • Special Ope!ato!s ( I ! )IC ! *C0"CC ! I&  • SPECIAL OPERATORS <# IN – IN – it is used for evaluating multiple values. E' 3 <# )ist <# )ist the employees in dept 1: @ +:

8# )ist all the cler#s and analysts

"e can provide upto 1::: values at the ma%

8# LIE – LIE – used for pattern matching ? "pe!centa.e# - matches : or ;n< characters 1: 7  a g e

@ "un&e!sco!e# J "un&e!sco!e# J matches e%actly one character E' 3 <# List all te emplo%ees 4ose name sta!ts 4it 9S

"henever we use U or V ! always ensure that it is preceded by the word 9li/e 8# List Lis t te emplo%ee emp lo%ees s 4ose name n ame is a;in. a ;in. lette! l ette! 9L as 8  n& ca!acte!

ASSINMENT <# List te emplo%ees emp lo%ees 4ose name is i s a;in. atleast atl east 8 Ls Ls

8# List List te te empl emplo% o%ee ees s 4os 4ose e name name is a;i a;in. n. lett lette! e! 9E 9E as te te last last but but one one ca!acte!

># List all te emplo%ees 4ose 4o se name is a;in. a;in . lette! 9R in te >  !& position

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In the above ?uery! we give + underscores before U. # List all te emplo%ees 4o a!e a;in. e'actl% = ca!acte!s in tei! obs

Qere ! in single ?uotes – we give 4 underscores. =# List te emplo%ees 4ose name is a;in. atleast = ca!acte!s

Qere! also in single ?uotes – we give 4 underscores ( VVVVV 

># BETEEN operator BETEEN operator – used for searching based on range of values. E' 3 <# )ist the employees whose salary is between +:: and 2::

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# IS operator – it is used to compare nulls E' 3 <# )ist all the employees whose commission is null

ASSINMENT <# List all te emplo%ees 4o &ont a;e a !epo!tin. mana.e!

LOICAL OPERATORS <# List all te salesmen in &ept >1

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8# List all te salesmen in &ept numbe! >1 an& a;in. sala!% .!eate! tan <=11

># List all te emplo%ees 4ose name sta!ts 4it 9s o! 9a

# List all te emplo%ees e'cept tose 4o a!e 4o!/in. in &ept <1  81$

=# List te emplo%ees 4ose name &oes not sta!t 4it 9S

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F# List all te emplo%ees 4o a!e a;in. !epo!tin. mana.e!s in &ept <1

ASSINMENT <# List te emplo%ees 4o a!e not 4o!/in. as mana.e!s an& cle!/s in &ept <1 an& 81 4it a sala!% in te !an.e o( <111 to >111

8# List List te emplo%e emplo%ees es 4ose 4ose sala! sala!% % not not in te !an.e !an.e o( <111 <111 to 8111 8111 in &ept &ept <1+81+>1 e'cept all salesmen 14 7  a g e

># List te &epa!tment names 4ic a!e a;in. lette! 9O in tei! locations as 4ell as tei! &epa!tment names

SORTIN It arranges the data either in ascending / descending order Ascending – A&> / Descending – DC&> "e can sort the data using ORDER BG  *y default! the data is always arranged in A&> order *o! e' 3 <# A!!an.e all te emplo%ees b% tei! sala!%

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8# A!!an.e all te emplo%ees b% tei! sala!% in te &escen&in. o!&e!

># A!!an.e ename+ sal+ ob+ empno an& so!t b% &escen&in. o!&e! o( sala!%

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In the above ?uery we have – o!&e! b% 8 – 8 – thus it arranges only the + nd column ;salary< in the descending order.  0hus to arrange the specic columns in order – we must have to specify the column number. NOTE :- ORDER BG  should  should be used always as the last statement in the &) ?uery.

Selectin. DISTINCT AL)ES

 0he above ?uery ?uery arranges arranges all the distinct distinct values values of department department number. number.

CHAPTER 

RO)P (unctions an& !oupin.

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"e have = RO)P functions! RO)P functions! 1 &um + ,a% 2 ,in 3 Avg 4 >ount Sum 3 returns total value Ma' – Ma' – returns ma%imum value Min – Min – returns minimum value A;. – A;. – returns average value Count 3 returns number of records E' 3 <# &isp &ispla la% % te te ma'i ma'imu mum m sala sala!% !%++ mini minimu mum m sala sala!% !% an& an& tota totall sala sala!% !% (!om (!om emplo%ee

To !i"e !i" e #li#ses #li# ses for f or the colu$%s colu $%s :-

># Te belo4 2ue!% .i;es te total numbe! o( emplo%ees

# Te belo4 2ue!% .i;es te numbe! o( emplo%ees 4o a;e commission

=# List te numbe! o( emplo%ees in &epa!tment >1

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ASSIMENT <# Displa% te total sala!% in &epa!tment >1

8# List te numbe! o( cle!/s in &epa!tment 81

># List te i.est an& lo4est sala!% ea!ne& b% salesmen

RO)PIN It is the proce process ss of compu computin ting g the aggre aggregat gates es by segre segregat gating ing based on one or more more columns. +: 7  a g e

=rouping is done by using 9.!oup b% clause. b% clause. *o! e' 3 <# Displa% te total sala!% o( all &epa!tments

8# Displa% te ma'imum o( eac ob

HAIN 9Ha;in. is 9Ha;in.  is used to lter the grouped data. 9e!e is 9e!e is used to lter the non grouped data. ;Ha;in. should Ha;in.  should be used after .!oup b% clause b% clause 9e!e should 9e!e should be used before .!oup b% clause b% clause *o! e' 3 <# Displa% ob-4ise i.est sala!% onl% i( te i.est sala!% is mo!e tan Rs<=11

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8# Displa% Displa% ob-4is ob-4ise e i.est i.est sala!% onl% i( te i.est i.est sala!% is mo!e tan <=11 e'clu&in. e'clu&in. &epa!tment >1$ So!t te &ata base& on i.est sala!% in te ascen&in. o!&e!$

RESTRICTIONS ON RO)PIN J we can select only the columns that are part of ;.!oup ; .!oup b% statement b% statement If we try selecting other columns! we will get an error as shown below!

 0he above ?uery is an error error because  ob<  ;ob< is there in the select ?uery select ?uery but not in the .!oup b% ?uery. b% ?uery. If it is enclosed in any of the .!oup (unctions li/e sum"sal# etc sum"sal#  etc – then it is not an error. *ut whatever table is included in the select ?uery select ?uery must also be included in the .!oup b% ?uery.  0he above problem problem can be overcome overcome with the following following ?uery ?uery as shown shown below!

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 0he below ?uery ?uery is also also correct correct to rectify rectify the above error! error!

"hatever is there in the select statement select statement must be there in the .!oup b% statement. b% statement. *ut! whatever is there in the .!oup b% statement b% statement need not be present in the select statement. select statement.  0his is shown shown in the above above two corrected corrected ?ueries. ?ueries. ASSINMENT <# Displa% te &epa!tment numbe!s alon. 4it te numbe! o( emplo%ees in it

8# Displa% te &epa!tment numbe!s 4ic a!e a;in. mo!e tan  emplo%ees in tem

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># Displa Displa% % te ma'imum ma'imum sala!% sala!% (o! eac o( te ob e'clu&i e'clu&in. n. all te emplo%ees emplo%ees 4ose name en&s 4it 9S

# Displa Displa% % te &epa!tment &epa!tment numbe!s numbe!s 4ic a!e a;in. a;in. mo!e tan 111 as tei! &epa!tmental &epa!tmental total sala!%

NOTE :  0o  0o clear the screen! screen! the command used used is! cl sc! J if it is a large ?uery and we cannot type it repeatedly! then type in – S,L 0 e& J when we type e& J J we get the notepad – after ma#ing the necessary changes – then clic# on the 9' i.e! 9' i.e! the close button at the top right corner – then clic# on %es when %es when a dialog bo% as#ing whether to overwrite the le comes – after this it comes to the oracle screen – in the ne%t line ! enter ;K ;K ; and hit on ente! button ente! button – another way of ending the ?uery is by typing ; K ;  K ; in the ne%t line of the ?uery – this indicates the end of the ?uery.

CHAPTER &

STATEMENTS

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Statements 3 they help us to create the table and insert the data.  0here are are 2 types of statements! statements!  DDL – Data Denition )anguage – the various commands in DD) are PJ >reate! Drop!  0runcate!  0runcate! Alter! Alter! ename ename DML L – Data ,anipulation )anguage – the various commands in D,) are PJ Insert!  DM Bpdate! Delete  TCL – 0ransaction >ontrol )anguage – the various commands in 0>) are PJ ollbac#! >ommit! &avepoint CREATE – CREATE – It creates the table. *efore we study the C!eate command! C!eate command! let us rst study the some of the basic &atat%pes we use in &). <# CHAR PJ CHAR PJ It stores the %ed length character data. It can store the alphanumeric data (i.e! numbers and characters. 8# ARCHAR It stores the variable length character data It can store alphanumeric alphanumeric data. Die!ence bet4een CHAR  ARCHAR )et us consider an e%ample as shown below to e%plain the dierence. N#$e ch#r '() * Qere we are dening name which name which is of 5characters in length. ow! let us store ; To$< in the name eld. )et us understand how the memory is allocated for this!

Blan/ Space

T

O

M

-

-

-

Rese!;e& K Non-!eusable memo!% +4 7  a g e

"hen we declare anything of type ca!! ca!! the memory is allocated as of the siEe given and its %ed length – hence it cannot be altered. ow! when we give to$! it allocates 5 bytes for name ca! – ca! – only the 1 st 2bytes are used to store Tom – om – the rest becomes waste as it is a blan# space and it is reserved memory.  0he len.t"name#  F F.. Name ;a!ca! "F# J Qere we are dening name which name which is of 5characters in length. ow! let us store ; To$< in the name eld. )et us understand how the memory is allocated for this! Null

T

O

M

$

$

$

Re-usable memo!% "hen we declare anything of type ;a!ca!! ;a!ca!! the memory is allocated as shown above and it is variable length "hen we give to$! it allocates 5bytes for name ;a!ca! – ;a!ca! – only the 1 st 2bytes are used to store tom – tom – the remaining 2 elds becomes null. null. As we #now the property of null – null – null does not occupy any memory space 3 space  3 tus te memo!% is not 4aste& e!e$  0he len.t"name#  > >.. Anote! &ie!ence is P is P J In ca!! ca!! ma%imum value we can store is +::: characters In ;a!ca!! ;a!ca!! ma%imum value we can store is 3::: characters. ># N)MBER J it stores numeric data. *o! e' 3 <# sal numbe!"# J Qere the ma%imum possible value is 9999. 8# sal numbe! "F+ 8# J Qere! + – scale (total number of decimal places 5 – precision (total number of digits including decimal places ,a%imum value is 9999.99 sal numbe! "+ ># J ma%imum value is 9.999 sal numbe! "8+ 8# ma%imum value is .99 # DATE J it stores date and time +5 7  a g e

J no need to specify any length for this type. *o! e'+

&) K orderVdt DA0C H

Date is always displayed in the default format PJ

&& 3 mont 3 %%

NOTE :;a!ca!8 – ;a!ca!8 – from 1:g! varchar @ varchar+ are the same. Carlie Carlier! r! varc varchar har was was suppor supportin ting g upto upto +::: +::: charac character ters s and varc varchar har+ + was supporting supporting upto 3::: characters.

=# BLOB &tands for – *inary )arge 'b$ect It stores binary data (images! movies! music les within the database. It stores upto 3=*. F# CLOB &tands for – >haracter )arge 'b$ect It stores plain character data li#e ;a!ca! eld ;a!ca! eld upto 3=*. C!eate te (ollo4in. tables PROD)CTS P!o&ID " P # P!o&Name " Not Null # ,t% " C/ 0 1 # Desc!iption ORDERS P!o&ID " * (!om p!o&ucts # O!&e!ID " P # ,t%@sol& " c/ 0 1 # P!ice O!&e!@Date

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e can see tat te table as been c!eate&$ ow! let us verify if the table has really been created and also the description of the table!

 0he new table table p!o&ucts has p!o&ucts has been added to the database.

 0hus! we get get the description description of the table table p!o&ucts. p!o&ucts.

 0he new table table o!&e!s has o!&e!s has been created. "e can see from the above ?uery how to reference a child table to the parent table using the !e(e!ences #eyword. !e(e!ences  #eyword.

+8 7  a g e

 0hus we can can verify that o!&e!s table o!&e!s table has ben created and added to the database.

 0hus! we get get the description description of the o!&e!s table. o!&e!s table. C!eatin. a table (!om anote! table PJ table  PJ ow! we will see how to create a table from another table – i.e! it duplicates all the records and the characterstics of another table.  0he &) ?uery ?uery for it is is as follows! follows!

 0hus we can can see that we have have created created another table table temp from temp from the table &ept. &ept. "e can verify it as shown below!

 0hus! we can can see that the table temp has temp has been created.

+9 7  a g e

 0hus! we can see that the table temp has temp has copied the structure of the table &ept. &ept. Qere! we must observe that temp copies temp copies all the columns! rows and '0 B)) constraints only from the table &ept. &ept. It never copies ! -! >hec# constraints. Tus+ 4en in te inte!;ie4 somebo&% as/s %ou 5I a;e a table 4ic as about
 0hus! from the above ?uery – we can see that all the records records of the table &ept has &ept has been copied into the table temp. temp. TR)NCATE It removes all the data permanently! but the structure of the table remains as it is. E' 3 S,L 0 TR)NCATE TABLE test J DROP It removes both data and the structure of the table permanently from the database. E' 3 S,L 0 DROP TABLE test J )et )et us unders understan tand d the the dier dierenc ence e betwee between n &!op &!op  t!unc t!uncate ate using using the below below shown shown e%ample!

)et us create + tables 0est1 and 0est+ as shown above.

2: 7  a g e

 0he above shows shows the description description of the the table test1.

 0he above gives gives the description description of the the table 0est+. 0est+. ow! let us use the ow! the T!uncate 2ue!% on Test<  Test<  and D!op 2ue!% on Test8  Test8   and see the dierence.

21 7  a g e

 0he above 2 ?ueries show show that – 1st ?uery has the table test1 truncated. +nd ?uery ?uery – it shows shows no !o4s selecte& – selecte&  – thus only the records from the table has been rd removed. 2  ?uery – it shows that the structure of the table is still present. 'nly the records will be removed.  0hus! this e'plains te t!uncate 2ue!%$

 0hus from the above ?ueries we can e%plain how &!op wor#s. &!op wor#s. 1st ?uery – it drops the table.  0hus – the entire entire structure structure and and records records of the table are dropped. dropped. nd rd +  and 2  ?uery – since! there is no table – select  &esc ?uery &esc  ?uery for test8 will test8 will throw an error.  0hus! this e'plains te &!op 2ue!%$ Qence! we have seen the dierence between &!op  t!uncate ?uery. t!uncate ?uery. <1. Rec%cle Bin

TABLE DROP

RECGC LE BIN at to &o

*LASHBAC 

RESTORE IT

P)RE

PERMANENTLG REMOE

2+ 7  a g e

 0he functionality functionality of ecycle ecycle *in was introduced introduced in 'racle 1:= version only. only. 0hus even though the table has been dropped! we can still restore it using asbac/ comman& or we can permanently remove it using the pu!.e command.  0his concept concept of ecycle ecycle bin was was not there there in the earlier versions of of 'racle. RENAME It renames a table. *o! e'+ let us see the ?uery of how we do this renaming a table.

In the above 2?ueries – we have created a table temp which temp which copies table &ept – &ept – we see the records records of the table temp – and also chec# if the table has really been created. created. ow let us !ename temp to temp8> as temp8>  as shown below!

 0he above ?uery ?uery is used to rename rename a table. ow let us verify the contents of the table and chec# if it has really been modied! &ee ne%t page!

22 7  a g e

 0hus the table table has been renamed renamed and its contents are are veried. ALTER J this ?uery alters / changes the structure of the table (i.e! J adding columns! removing columns! renaming columns etc . ow let us alte! the table p!o&ucts (which p!o&ucts  (which we have created earlier. <# Let us a&& a ne4 column +$o,el%o to te table$

 0hus! a new column has been added. )ets verify verify it with with the ?uery shown below! below!

8# No4 let us &!op te column mo&el@no (!om p!o&ucts$ 23 7  a g e

 0hus! the column column has been been dropped. dropped.

 0hus! we can see from the description description of the table – the column mo&el@no  mo&el@no  has been dropped. ># Let us !ename te column .ty  to  to .ty#"#il#ble.

)et us verify if it has been renamed!

NOTE : SE/ECT is neite! DML no! DDL$ It &oes not belon. to an% .!oup because it &oes not alte! an%tin.+ it ust &ispla%s te &ata as !e2ui!e& b% te use! .

DML 24 7  a g e

INSERT It inserts a record to a table. )et us observe how it is done!

 0his is how we insert values into a table. All characters and alphaJnumeric characters(e% – 1::+2sdf68 must be enclosed in single ?uotes (; ;  and each value must be separated by comma. Also we must be careful in entering the data without violating the primary #ey! foreign #ey ! uni?ue constraints. ow let us see the table in which the data in has been inserted!

ow! let us insert data into the table o!&e!s in o!&e!s in which a foreign #ey is referencing primary #ey!

Qere! we see that 1::1 is the same prodid as of the earlier table. &ysdate – it displays the current date set in the system .

ow! let us see the table!

Another way of inserting data into the table is shown below! 25 7  a g e

ow! let us see the table!

)PDATE PJ )PDATE PJ It updates one or more records. *o! e' 3 <# )et <# )et us update salary by increasing it by s+:: and also give commission of  s1:: where empno G 6259.

ow! let us up&ate the said record as shown below!

)et us verify if the record has been updated! 26 7  a g e

 0hus! the record(em record(empno pno – 6259 has been updated. 8# Inc!ease all sala!% b% <1?

)et us verify it!

DELETE 28 7  a g e

It deletes one / some / all the records. )et us create a table test from table emp – and see how to delete 1 record and how to delete all records from it!

 0hus! we have have created created the table test.

 0hus 1 row! row! ;miller< has been deleted. deleted.

 0hus! the deletion deletion has been been conrmed. conrmed.

TCL Any D,) change on a table is not a permanent one. 29 7  a g e

"e need to save the D,) changes in order to ma#e it permanent "e can also undo (ignore the same D,) changes on a table.  0he DD) changes changes cannot be be undone as they are are implicitly saved. ROLLBAC  It undoes the D,) changes performed on a table. )et us see in the below e%ample how !ollbac/  wor#s!  wor#s!

)et us delete the employee table. "hen we perform select operation select operation on emp! we can see that all the rows have been deleted. "e now perform the !ollbac/  operation!  operation!

ow let us perform the select operation! select operation!

 0hus performing performing the !ollbac/  operation!   operation! we can retrieve all the records which had been deleted. COMMIT It saves the D,) changes permanently to the database. 3: 7  a g e

Committin. a(te! !ollbac/  ;ice ;e!sa 4ill not a;e an% eect )et us e%plain the above statement with an e%ample!

"e can see that commit has commit has no eect after !ollbac/  operation.  operation.

 0hus! from from above – we we can see that !ollbac/  has  has no eect after commit operation. commit operation. During an abnormal e%it – i.e! shutdown or if the &) window is closed by mouse clic# – then all the D,)
During a normal e%it – e'it J J J J all the D,)  "hen we perform the following operations in the same order for a table – then I&C0! BDA0C will be committed – because A)0C is a DD) – and thus all the D,)  Qere! all are rolled bac#. SAEPOINT P SAEPOINT P It is li#e a pointer (brea#Jpoint till where a D,) will be rolled bac#. E' :Insert W &ave point % H Bpdate W Delete .. ollbac# to % H W W Qere! only DC)C0C @ BDA0C are rolled bac#. I&C0 is neither rolled bac# nor committed.

Assi.nments <# C!eate te (ollo4in. tables a 0able name PJ &0BDC0& regno ( name ( 3+ 7  a g e

semester D'* hone b 0able name PJ *''& boo#no ( bname author c 0able name PJ )I*AN regno (- from students boo#no (- from boo#s D'I –date of issue D' – date of return 8# Inse!t = !eco!&s to eac o( tese tables ># Die!entiate bet4een+ a# Delete an& T!uncate b# T!uncate an& D!op c# Ca! an& a!ca! &# D!op an& Delete Delete and 0runcate 0runcate a Delete – deletes whichever records we want to delete from the table  0runcate  0runcate – deletes deletes all the records records whether whether we want it it or not b

Delete – can be undone  0runcate  0runcate – cannot cannot be undone.

NOTE – 0he 0he rim rimar ary y ey crea create ted d usin using g mor more than than 1 colu column mn is call called ed as co$posite  pri$#ry 0ey . C% – alte! table lib A&& p!ima!% /e% "!e.no+ boo/no+ DOI# H DOI#  H

CHAPTER (

S)B - ,)ERIES

A subJ?uery is also called as a nested ?uery. 32 7  a g e

S%nta' o( a sub-2ue!% Select  *!om  e!e 

O)TER ,)ERG

" select   *!om   e!e  # INNER ,)ERG 

Qere! the inne! 2ue!% will 2ue!% will be e%ecuted rst.  0he output of inne! 2ue!% is 2ue!% is passed as input to the oute! 2ue!% 2u e!%$$  0o  0o write a subJ?uery! subJ?uery! atleast atleast 1 common common column should should be e%isting e%isting between between the tables. *o! e' :<# List te emplo%ees 4o!/in. in 9Resea!c &epa!tment$

8# List te &epa!tment names tat a!e a;in. anal%sts

># List te emplo%ees in Resea!c an& Sales &epa!tment

33 7  a g e

Assi.nment <# List te &epa!tment names 4ic a!e a;in. salesmen salesmen in it$

8# Displa% te emplo%ees 4ose 4ose location is a;in. atleast one 9O in it$

># List te &epa!tment names tat a!e a;in. atleast < emplo%ee in it$ 34 7  a g e

# List te &epa!tment names tat a!e a;in. atleast  emplo%ees in it

=# Displa% te &epa!tment names 4ic a!e a;in. atleast 8cle!/s in it

F# Disp D ispla% la% te t e 8 n& ma'imum sala!%

Q# Disp D ispla% la% te t e > !& ma'imum sala!%

# Disp D ispla% la% te t e  t least sala!% 35 7  a g e

 0his method is not eRcient to nd the ma%imum and minimum salary. salary. 0he limit is 2+. 0his th is not eRcient if you want to nd the 1::  ma%imum salary. e can a;e upto >8 le;els o( sub-2ue!ies onl%$ # List te &epa!tment names tat a!e a;in. no emplo%ees at all

CHAPTER 

 OIN 36 7  a g e

 oins are used when we need to fetch the data from multiple tables T%pes o( OIN"s#  >artesian Xoin (product  Inner (C?ui Xoin -ull 'uter Xoin  'uter Xoin J )eft 'uter Xoin! ight 'uter Xoin! -ull  &elf Xoin CARTESIAN OIN J It is based on >artesian product theory. Ca!tesian P!o&uct Teo!% in Teo!% in ,athematics states that PJ )et there be two sets – A Y1! +! 2Z @ * Y3! 4Z  0hus the >artesian >artesian product product (A* will will be! A  * G Y (1!3! (1!4! (+!3! (+!4! (2!3! (2!4 Z  0hus there are 5 sets – order of A is 2 @ order of * is +. 0herefore! 0herefore! +2 G 5 is the >artesian product.

Qere! each and every record of the 1 st table will combine with each and every record of the +nd table. If a table A is having 1: records @ * is having 3 records – the >artesian $oin will return 1:3 G 3: records. *o! e'+ let us consider the following ?uery Displa% emplo%ee name alon. 4it te &epa!tment name

38 7  a g e

-rom above – we can see that the above ?uery returns 45 records – but we are e%pecting 13 records. 0his is because each and every record of employee table will be combined with each @ every record of department table.  0hus! >artesian >artesian $oin should should not be used used in real time scenarios.  0he >artesian $oin contains both correct correct and incorrect incorrect sets of data. "e have to retain the correct ones @ eliminate the incorrect ones by using the inne! oin. oin. INNER OIN Inner $oin are also called as e2uioins. e2uioins.  0hey return return the matching matching records records between between the tables. tables. In the real time scenarios! this is the most fre?uently used Xoin. *o! e'+ consider the ?uery shown below! &elect A.ename! A.sal! *.dname -rom emp A! dept * "here A.deptno G *.deptno And A.sal K +::: 'rder by A.sal H

J OIN con&ition con&ition - *ILTER *ILTER con&ition co n&ition

)et us see the output shown below!

39 7  a g e

 X'I condition condition is mandatory mandatory for removing removing the >artesian >artesian output. output. )et us consider the following + scenarios shown below! Scena!io < P

A ,

R

P

B S

T

P

C 

G 

P

e 4ant , S



Te S,L 2ue!% 4ill be+ Select A.! Select A.! A.! *.&! >.[ -rom A! *! > "here A. G *. Numbe! o( oins  8 And A. G >. Te! Te!e( e(o! o!e+ e+ Numb Numbe! e!

o( OIN OINS S



Numb Numbe! e!

o( 

Scena!io 8 A

4: 7  a g e

P

,

R

B P

,

S

P

C 

G 

,

e 4ant R

P

T

S



 0he S,L 2ue!% is + &elect A.! A.! A.! *.&! >.[ -rom A! *! > "here A. G *. And A. G *. Numbe! o( oins  > And A. G >. H

Te!e( Te!e(o!e o!e++ Numbe Numbe!! o( OIN OINS S  Numb Numbe! e! o( commo common n If there are no common columns! then re$ect it saying that the two tables can be $oined. *ut there are some cases – where the + columns will be same but having dierent column names. *o! e' 3 customerid customerid @ cid Displa% emplo%ee name+ is ob+ is &name an& is location (o! all te mana.e!s li;in. in Ne4 Go!/ o! Cica.o

ANSI st%le OINS  0his was introduc introduced ed from 'racle 'racle 9i. It is another way of writing inner $oins with a few modications. 41 7  a g e

 0hus we! can can see the changes changes ! nd  In the +  line J !(comma has been replaced by the word ;$oin< rd  In the 2  line – ;where< has been replaced with ;on< Assi.nment <# Displa Displa% % emplo%ee emplo%ee name an& is &epa!tme &epa!tment nt name (o! te emplo%ees emplo%ees 4ose 4ose name sta!ts 4it 9S

O)TER OIN It returns both matching and nonJmatching records 'uter $oin G inner $oin F nonJmatching records onJmatching records means data present in one table! but absent in another table w.r.to common columns. *o! e'+ 3: e'+ 3: is there in deptno of dept table! but not there in deptno of emp table. Displa% all te &epa!tment names i!!especti;e o( an% emplo%ee 4o!/in. in it o! not$ I( an emplo%ee is 4o!/in. 3 &ispla% is name$ 4+ 7  a g e

si%! ri!ht oi%

si%! left oi%

si%! full oi%

A

B

<1

F

>

>

Q > A C B  F1!eco!&s A I B  >!eco!&s"> matcin.# A L B  <1!eco!&s ">matcin. U Qnon matcin. o( A# A R B  F!eco!&s ">matcin. U >non matcin. o( B# A * B  <>!eco!&s ">matcin. o( A  B U Qnonmatcin. o( A U >nonmatcin. o(  B# Assi.nment <# Displa Displa% % emplo%ee emplo%ee name an& is &epa!tme &epa!tment nt name (o! te emplo%ees emplo%ees 4ose 4ose name sta!ts 4it 9S 42 7  a g e

8# Displa% emplo%ee name an& is &epa!tment name nam e 4o is ea!nin. ea!ni n. <  st ma'imum sala!%

SEL* OIN  Xoining a table table to itself is called self $oin  0he *ROM clause *ROM clause loo#s li#e this! -', emp A! emp * 'r -', -', emp emp A $oin $oin emp emp * J ANSI style -or e%! J Displa% emplo%ee name alon. 4it tei! mana.e! name

No4+ let us see o4 tis i$e te lo.ic "te abo;e 2ue!%# 4o!/s+ 43 7  a g e

Emp "B# EmpNo 1:1 1:+ 1:2 1:3 1:4

Ename &cott *la#e ing &mith Xones

M.! 1:+ 1:2 J 1:2 1:3

ow! when we give the above ?uery – in 'racle – it starts matching the ; m.!< m.!< column of  emp A with A with the ;empno ; empno<< of emp b – b – we get two tables because in sel( oin – oin – a duplicate of  the table re?uired is created. ow let us conside ow considerr the the V!st emplo%ee Scott – it star starts ts the the m.!i& of Scott  Scott  with the empno of all the recor records ds in emp B – when when two two i&s match match!! then the empno in emp B becomes the m.! of m.! of the empno in empno in emp A. A. 0hus! we can see that – m.! i& 1:+ i& 1:+ is matching with empno 1:+ empno 1:+ Bla/e in Bla/e in emp B. B. 0herefore! *la#e is the manager of &cott. &imilarly we do the same for all the other records of emp A and A and thus nd the employees and their respective managers. Displa% te emplo%ees 4o a!e .ettin. te same sala!%

Co 3 !elate& ,ue!ies : → → → →

 0hey are are special type of sub – ?ueries ?ueries Qere! both outer @ inner ?ueries are interJdependent -or each @ every record of outer ?uery! the entire inner ?uery will be e%ecuted  0hey wor# on on the principles principles of both sub 3 2ue!ies  OIN"s#. OIN"s# .

*o! e'+ Displa% te emplo%ee 4o is ea!nin. te i.est sala!%

44 7  a g e

 0hus! if an outer ?uery column is being accessed inside the inner ?uery! then that ?uery is said to be coJrelated. )et us see the logic i.e! how we get the 1 st ma% salary PJ Emp "A# EmpNo

Ename

1:1

&cott

1:+

*la#e

1:2

ing

1:3

&mith

1:4

Xones

Sal 2:: : 3:: : 4:: : +:: : 1:: :

Emp "B# EmpNo Ename 1:1

&cott

1:+

*la#e

1:2

ing

1:3

&mith

Sal 2:: : 3:: : 4:: : +:: : 1:: :

&ince coJrelated ?ueries are a combination of Xoins and subJ?ueries. 1:4 Xones It follows the concept of Xoins and creates multiple copies of   the same table.  0hen it ta#es 1 st record i.e! J *la#e – sal is 2:::. It starts comparing with the sal in the emp table! 2::: G 2::: J count starts from : – thus! : G : 2::: S 3::: – thus! : T G 1 2::: S 4::: – thus! : T G + 2::: K +::: – thus ! :T G + 2::: K 1::: – thus! : T G + if the condition becomes false! then the count increments by 1. Qere 2::: is less than 3::: @ 4:::! thus : T G +. 0hus ! *la#e does not have the highest salary. &imilarly! it does for the ne%t records! *la#e – salary of 3::: – but 3::: S 4::: – thus! : T G 1. 0his is also false. ing – salary of 4::: – it is greater than everything – thus! : G :. 0hus! ing has the highest salary. *ut the ?uery doesn !& ma'imum sala!% 3 a(te! %ou 4!ite te 2ue!% 3 te% 4ill as/ %ou to e'plain te lo.ic as to o4 it .ets te same 3 &!a4 te table an& e'plain it to tem ust as so4n abo;e$ 45 7  a g e

Assi.nment <# Displa% te least sala!% (!om te emplo%ee table$

8# Displa% top > pe!sons sala!ies (!om te emplo%ee table$

># !ite a 2ue!% to &ispla% bottom > sala!ies

# Displa% Dis pla%
46 7  a g e

=# Displa% Dis pla%
48 7  a g e

CHAPTER 4

*)NCTIONS

-unctions – it is a reJusable program that returns a value.  0here are are 8 t%pes! t%pes! re – dened • Bser dened • P!e 3 &eVne& → ='B functions → >QAA>0C functions → B,CI> functions → DA0C functions → &C>IA) functions  0hese are used both in &) and )/&). ) – rocedural rocedural )anguage (it
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ow! let us study the various >QAA>0C functions. CHARACTER (unctions a Bpper b )ower c )ength *o! e' :-

In the 1st ?uery! we see something called as &ual. &ual. Dual 3 is a dummy table which is used for performing some independent operations which will not depend on any of the e%isting tables. *o! e'+ 1

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 0his gives gives the system date.

+

2

"e use dual – when the data is not present in any of the e%isting tables. 0hen we use dual. Len.t – Len.t – it returns the length of a given string. *o! e'+ <#

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8#

># Displa% all te emplo%ees 4ose name  ob is a;in. e'actl% = ca!acte!s

REPLACE It replaces the old value with a new value in the given string. *o! e'+

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Qere! a 3 is the old value to be replaced with p – which is the new value.

 0his ?uery ?uery replaces all the names names which has ;A< in it with with ;*<. )et us see the output as shown below!

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S)BSTR  0his is called called subst!in.. subst!in. . It e%tracts ;n< characters from %(th position of a given string. *o! e'+

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Qere + "ob+ 9< + 9># – 9># – means from ob from ob –  – e%tract (!om ca!acte!s. ca!acte!s . <# Displa% te emplo%ees 4ose ob sta!ts 4it 9man

8# Displa% te emplo%ees 4ose ob en&s 4it 9man

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INSTR  0his is also also called as inst!in.$ It returns position of a given character in a given string. *o! e'+ Select i%str '+or#cle5 6 +#5 6 1 6 1) fro$ ,u#l *

=iven string

>haracter to be searched osition from where the search should begin umber of occurences

Displa% all te t e emplo%ees 4ose name is i s a;in. 9L 9 L

List te emplo%ees 4ose ob is a;in. atleast 8 As in it 55 7  a g e

CONCAT It concatenates any two values or columns. It is represented by J WW *o! e'+

N)MERIC *)NCTIONS 1 Mo& PJ Mo& PJ it returns the remainder when 1 number is divided by the other.

Displa% te emplo%ees ea!nin. o&& numbe!e& sala!ies$ 56 7  a g e

Roun& It rounds o a given number to the nearest decimal place. T!unc It trunc truncate ates s the given given number number to the given given decima decimall place place.. 0runcat runcate e does does not do any rounding. *o! e'+

Qere! ;< ;<< indicates the number of positions. DATE DATE *)NCTIONS <# S%s&ate &tands for &ystem date. It returns both date @ time! but by default – only date is displayed.  0he default format format is! && 3 mon 3 %%

8# S%stimestamp Introduced from 'racle 9i eturns date! time and timeEone.

Qere! $<111 – $<111 – gives the fraction of millisecond which #eeps changing as shown below!

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co%t#i%s fr#ctio%s fr#ctio%s of # seco%, 7  In inte!;ie4 3 i( te% as/ %ou 3 7 which fu%ctio% co%t#i%s  3 ten ans4e! is 5SGSTIMESTAMP7$ OR 7how to see the syste$ ti$e 7  3

SPECIAL *)NCTIONS <# TO 3 CHAR Bsed for displaying the date in dierent formats. *o! e'+

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No4+ let us see o4 to a&& = !s to te e'istin. time+

"e can see that 4 hrs has been added to the current time.

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It substitutes a value for a null. *o! e'+

 0he above ?uery means – if the employee has commission! commission! then add sal F comm. 0o get total salary – else add : to the sal and display total salary. DECODE It wor#s li#e ;i( ;i( 3 ten 3 else< else < statement. *o! e'+

 0he above ?uery states that – in $ob! if cler# is there! replace with > – else if salesman is there! replace it with & – else replace with ;'<. Displa% emplo%ee name+ ob+ sala!% an& commission$ I( te commission is N)LL+ ten &ispla% -<11 61 7  a g e

Displa% all emplo%ees 4ose name is a;in. a; in. e'actl% < 9L in it

CHAPTER 8

NORMALIXATION 6+ 7  a g e

No!mali6ation is the process of splitting the bigger table into many small tables without changing its functionality. It is generally carried out during the design phase of &D)>. A&;anta.es 1 it reduces the redundancy (unnecessary repeatation of data + avoids problem due to delete anamoly (inconsistency ormali orm aliEat Eation ion is a stepJ stepJby byJs Jstep tep proce process ss and and in each each step! step! we have have to perfor perform m some some activities. STEPS IN NORMALIXATION 1 1- – 1st ormal form + +- – +nd ormal form 2 2- – 2rd ormal form
8N*  0o  0o perform +-! J 0he tables have to be in 1J Qere! we identify all the complete dependencies and move them separately into dierent tables. At the end of +-! our data loo#s li#e this! ST)DENTS ego J 

BOOS *oo#o J   

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&name &emester D'* ,ailID hone

ego J -   *name Author D'I D' -ine

>N*  0he table will will have to be in in +Qere! we identify all the partial dependencies and move such columns to a separate table. ST)DENTS

BOOS

LIBRARG  

ego J  

*oo#o J  *name Author

*oo#o J -   ego J -   D'I D' -ine

&name &emester D'* ,ailID hone

Disa&;anta.e o( No!mali6ation  0he only minor disadvantage disadvantage is we may have to write comple% ?ueries as we have more number of tables to be accessed. Deno!mali6ation is Deno!mali6ation is the process of combining more than 1 smaller table to form 1 bigger table is called as denormaliEation. CODD !ules ( !ules ( Die!entiates bet4een DBMS  RDBMS  1 should support B)) values + should support creation of relationship between tables 2 should support DD)! D,)! 0>) 3 should support constraints li#e ! Bni?ue! >Q  4 should support ?uery techni?ues li#e sub – ?ueries! $oins! grouping etc. O!acle O!acl e i *eatu *eatu!es !es "i means inte!net# inte! net# J 0I,C&0A, datatype J &N&0I,C&0A, function J A&I style $oins J enaming a column O!acle <1. (eatu!es ". means .!i&# J ecycle *in ERD - Entit% Relationsip Dia.!am It is the pictorial representation of all the entities and their relationships (tables. ST)DENTS ego J   &name &emester D'* ,ailID hone

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ST)DENTS @ INTERNALS ego J -  &id ,ar#s

BOOS *oo#o J   *ame Author

LIBRARG  *oo#o J -  ego J -  D'I D' -ine

YY THE END YYYYY

ERG IMPORTANT

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