pl/sql interview q

8/19/2019 pl/sql interview q

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I am Brahma Reddy i am postgraduate and having 4 years of experience in oracle

technology in the areas of Unix, Pl/sql and Sql !urrently I am associated "ith xxx as

soft"are developer ,previously i "or#ed in yyy as a soft"are developer $y expert li#e

as creating procedure, function, pac#age and handling the exception, during the years i"or#ed di%erent domains, currently I am associated "ith xxx

What is diference between TRUNCATE & DELETE?

& 'runcate is a (() command

* +e can remove ul# amount of records at a time

- +e can.t rollac# the records

4 Release the space in dataase

'runcate reset the high "ater mar#

0 'runcate explicitly commit

& (elete is a ($) command

* +e can delete record y record

- +e can rollac# the records

4 !an1t release the memory in dataase

(elete can1t reset the "ater mar#

0 (elete implicitly commit

23R

5ns6 (i%erences6

'RU7!5'8 commits after deleting entire tale ie, cannot e rolled ac#

(ataase triggers do not 9re on 'RU7!5'8 (8)8'8 allo"s the 9ltered deletion

(eleted records can e rolled ac# or committed(ataase triggers 9re on (8)8'8

3. Diference between view and materialied view

(i%erence

:ie" is a logical tale

:ie" can hold the query

+e can1t create indexes on vie"


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/iews' 5 vie" is a virtual tale 8very vie" has a query attached to it 2'he query is a

S8)8!' statement that identi9es the columns and ro"s of the tale2s the vie" uses

0na"sh#t' 5 Snapshot is a recent copy of a tale from dataase or in some cases ,a

suset of ro"s/columns of a tale It is also #no"n as $ateriali>ed vie"D# a view c#ntain data?

5ns6 :ie"s do not contain or store data

+hat are the advantages of vie"s?

5ns6 Provide an additional level of tale security, y restricting access to a

predetermined set of ro"s and columns of a tale

@ Aide data complexity

@ Simplify commands for the user

@ Present the data in a di%erent perspective from that of the ase tale

@ Store complex queries

What is an 1racle se2$ence?

5ns6 5 Sequence generates a serial list of unique numers for numerical columns of a

dataase.s tales

What is a s,n#n,m?

5ns6 5 synonym is an alias for a tale, vie", sequence or program unit

What are the t,"es #% s,n#n,ms?

5ns6 'here are t"o types of synonyms private and pulic

What is a "rivate s,n#n,m?

5ns6 3nly its o"ner can access a private synonym

What is a "$blic s,n#n,m?

5ns6 5ny dataase user can access a pulic synonym

What is an 1racle inde+?

5ns6 5n index is an optional structure associated "ith a tale to have direct access to

ro"s, "hich can e created to increase the performance of data retrieval Index can e

created on one or more columns of a tale Index may also e considered as a ordered

list of content of a column

What is a schema?

5ns6 'he set of o=ects o"ned y user account is called the schema


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8xplicit !ursor6 5 cursor "hich is opened for processing data through a P)/SG) loc# is

#no" as 8xplicit !ursor

Attrib$tes 1% a 4m"licit C$rs#r'


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What is a tables"ace?

5ns6 5 dataase is divided into )ogical Storage Unit called talespaces 5 talespace is

used to grouped related logical structures together

4s se2$ence c,clic?5ns6 Kes

0elect nth hi9hest val$e %r#m a list #% val$es ?

5ns6 S8)8!' aempFname,asal ;R3$ emp a +A8R8 Ln @ &M 2S8)8!' !3U7'2(IS'I7!'

sal ;R3$ emp +A8R8 sal N asal

What are tri99ers and its t,"es?

5ns6 5 trigger is a piece of code attached to a tale that is executed after speci9ed ($)

statements executed on that tale 'here are &* types of triggers in P)/SG) that consist

of cominations of the B8;3R8, 5;'8R, R3+, S'5'8$87', '5B)8, I7S8R', UP(5'8,

(8)8'8 and 5)) #ey "ords6 ;or eg6 B8;3R8 5)) R3+ I7S8R' 5;'8R 5)) R3+ I7S8R'

B8;3R8 I7S8R' 5;'8R I7S8R'

What is the ma+im$m n$mber #% tri99ers can a""l, t# a sin9le table?

5ns6 &* triggers23racle

Diference between r#wid and r#wn$m?

5ns6 R3+I( is pseudo column in every tale 'he physical address of the ro"s is use to

for the R3+I(I7 A8D5(8!I$5) representation, R3+I( is sho"n as &O character string

of the follo"ing format BBBBBBBBBRRRR;;;; 2loc#, ro", 9le ;;;; is the 9leid of the

data9le that contains the ro" BBBBBBBBB is the address of the dataloc# "ithin the

data9le that contains the ro" RRRR is the R3+ 7U$B8R "ith the data loc# that

contains the ro" 'hey are unique identi9ers for the any ro" in a tale 'hey are

internally used in the construction of indexes

Ro"num is the sequential numer of ro"s in the result set o=ect

What is the %astest 2$er, meth#d %#r a table?

5ns6 By ro"id

What is the diference #% a LE(T :14N and an 4NNER :14N statement?

5ns6 5 )8;' 3I7 "ill ta#e 5)) values from the 9rst declared tale and matching values

from the second declared tale ased on the column the =oin has een declared on 5n

I778R 3I7 "ill ta#e only matching values from oth tales


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5#w can 4 av#id a divide b, er# err#r?

5ns6 Use the (8!3(8 function 'his function is asolutely rilliant and functions li#e a

!5S8 statement, and can e used to return di%erent columns ased on the values of

others4s view $"datable?

5ns6 3nly if the vie" is a simple hori>ontal slice through a single tale

What is D$al ?

5ns6 'he (U5) tale is a tale "ith a single ro" and a single column used "here a tale

is syntactically required

What is the diference between C5AR and /ARC5AR ?

5ns6 !A5R is 9xed length character type at storage level, and that :5R!A5R "ill e

variale length

D# we $se c#mmit in tri99ers.

5ns6 7o

5#w will the %etch the last inserted rec#rd in an, table ?

5ns6 select column &, column * ;rom "here ro"id M 2select max2ro"id from tale

What are c#nstraints and its t,"es?

Integrity !onstraint 6 5n integrity constraint is a declarative "ay to de9ne a usiness

rule for a column of a tale 5n integrity constraint is a statement aout a tale.s data

that is al"ays true

'ypes of integrity constraints 6 'he follo"ing integrity constraints are supported y

3R5!)86

& 73' 7U)) 6 disallo"s nulls 2empty entries in a tale.s column

* U7IGU8 6 disallo"s duplicate values in a column or set of columns

- PRI$5RK Q8K 6 disallo"s duplicate values and nulls in a column or set of columns

4 ;3R8IE7 Q8K 6 requires each value in a column or set of columns match a value in a

related tale.s U7IGU8 or PRI$5RK Q8K

!A8!Q 6 disallo"s values that do not satisfy the logical expression of the constraint

What is Re%erential 4nte9rit, and Re%erential inte9rit, c#nstraint ?

5ns6 Referential Integrity 6 Referential integrity de9nes the relationships among di%erent

columns and tales in a relational dataase It1s called referential integrity ecause the


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values in one column or set of columns refer to or must match the values in a related

column or set of columns

5 referential integrity constraint requires that for each ro" of a tale, the value in the

foreign #ey matches a value in a parent #eyWhat is 9r#$"s b, and havin9 cla$se? E+"lain with e+am"le

5ns6 Eroup y clause tells oracle to group ro"s ased on distinct values that exists for

speci9ed columns 'he group y clause creates a data set , containing several sets of

records grouped together ased on condition

Aaving !lause6 Aaving clause can e used "ith ER3UP BK clause Aaving imposes a

condition on the group y clause "hich further 9lters the group created y the ER3UP

BK clause Select ename,empno ;rom 8mpl Eroup y empno having empno N &C

What are L1C;0? What are t,"es #% diferent t,"es #% L#c


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& 8xclusive (() )oc#s

* Share (() )oc#s

- Brea#ale Parse )oc#s Restrictiveness of )oc#s 6 In general, t"o levels of loc#ing can

e used in a multi@user dataase6 8xclusive )oc#s 6 5n exclusive loc# prohiits thesharing of the associated resource 'he 9rst transaction to exclusively loc# a resource is

the only transaction that can alter the resource until the exclusive loc# is released

Share )oc#s 6 5 share loc# allo"s the associated resource to e shared, depending on

the operations involved 2eg, several users can read the same data at the same time

Several transactions can acquire share loc#s on the same resource Share loc#s allo" a

higher degree of data concurrency than exclusive loc#s

Diference between $ni2$e


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& !reate a cursor

* Parse the statement

- (escrie Results

4 (e9ning outputs Bind any variales

0 8xecute the statement

;etch ro"s of a query result

What d# ,#$ mean b, arsin9?

5ns6 Parsing 6 Parsing is the process of6 & 'ranslating a SG) statement, verifying it to e

a valid statement * Performing data dictionary loo#ups to chec# tale and column

de9nitions - 5cquiring parse loc#s on required o=ects so that their de9nitions do not

change during the statement.s parsing 4 !hec#ing privileges to access referenced

schema o=ects (etermining the execution plan to e used "hen executing the

statement 0 )oading it into a shared SG) area ;or distriuted statements, routing all

or part of the statement to remote nodes that contain referenced data

What is a 54NT and what are t,"es 54NT?

5ns6 Aints are suggestions that you give the optimi>er for optimi>ing a SG) statement

Aints allo" you to ma#e decisions usually made y the optimi>er

'KP8S 3; AI7'S 6

5))FR3+S 6 'he 5))FR3+S hint explicitly chooses the cost@ased approach to optimi>e

a statement loc# "ith a goal of est throughput

;IRS'FR3+S 6 'he ;IRS'FR3+S hint explicitly chooses the cost@ased approach to

optimi>e a statement loc# "ith a goal of est response time

;U)) 6 'he ;U)) hint explicitly chooses a full tale scan for the speci9ed tale

R3+I( 6 'he R3+I( hint explicitly chooses a tale scan y R3+I( for the speci9ed

tale

!)US'8R 6 'he !)US'8R hint explicitly chooses a cluster scan to access the speci9ed

tale

A5SA 6 'he A5SA hint explicitly chooses a hash scan to access the speci9ed tale

I7(8D 6 'he I7(8D hint explicitly chooses an index scan for the speci9ed tale


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57(F8GU5)6 'he 57(F8GU5) hint explicitly chooses an execution plan that uses an

access path that merges the scans on several single@column indexes 2Kou can specify

multiple indexes through this hint I7(8DF5S!6 'he I7(8DF5S! hint explicitly chooses

an index scan for the speci9ed tale If the statement uses an index range scan,3R5!)8 scans the index entries in ascending order of their indexed values

I7(8DF(8S!6 'he I7(8DF(8S! hint explicitly chooses an index scan for the speci9ed

tale If the statement uses an index range scan, 3R5!)8 scans the index entries in

descending order of their indexed values

3R(8R8( 6 'he 3R(8R8( hint causes 3R5!)8 to =oin tales in the order in "hich they

appear in the ;R3$ clause

US8F7) 6 'he US8F7) hint causes 3R5!)8 to =oin each speci9ed tale to another ro"

source "ith a nested loops =oin using the speci9ed tale as the inner tale

US8F$8RE8 6 'he US8F$8RE8 hint causes 3R5!)8 to =oin each speci9ed tale "ith

another ro" source "ith a sort@merge =oin

What d# $ mean b, E>CET41N4N4T ra9ma ?

5ns6 8D!8P'I37FI7I' Pragma 6 'o handle unnamed internal exceptions, you must use

the 3'A8RS handler or the pragma 8D!8P'I37FI7I' 5 VpragmaV is a compiler directive,

"hich can e thought of as a parenthetical remar# to the compiler Pragmas 2also called

VpseudoinstructionsV are processed at compile time, not at run time 'hey do not a%ect

the meaning of a program they simply convey information to the compiler 'he

prede9ned pragma 8D!8P'I37FI7I' tells the P)/SG) compiler to associate an exception

name "ith an 3racle error numer 'hat allo"s you to refer to any internal exception y

name and to "rite a speci9c handler for it Kou code the pragma 8D!8P'I37FI7I' in the

declarative part of a P)/SG) loc#, suprogram, or pac#age

using the syntax PR5E$5 8D!8P'I37FI7I'2exceptionFname, 3racleFerrorFnumer

"here VexceptionFnameV is the name of a previously declared exception ;or internal

exceptions, SG)!3(8 returns the numer of the associated 3racle error 'he numer

that SG)!3(8 returns is negative unless the 3racle error is Vno data found,V in "hich

case SG)!3(8 returns W&CC SG)8RR$ returns the message associated "ith the 3racle

error that occurred 'he message egins "ith the 3racle error code ;or user@de9ned

exceptions, SG)!3(8 returns W& and SG)8RR$ returns the message XUser@(e9ned


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8xceptionY unless you used the pragma 8D!8P'I37FI7I' to associate the exception

name "ith an 3racle error numer, in "hich case SG)!3(8 returns that error numer

and SG)8RR$ returns the corresponding error message 'he maximum length of an

3racle error message is &* characters including the error code, nested messages, andmessage inserts such as tale and column names

+hat do u mean y SP query?

5ns6 SP Guery 6 'he SP Guery is a standard query for numer to "ords conversion,

used especially for converting amount in numer into equivalent amount in "ords 'he

query is as follo"s 6 Select toFchar 2 toFdate 2 ZLno1, Z1 , ZSP1 "ords from dual ;or eg 6

Select toFchar 2 toFdate 2 .*-[4[.,.=. , .SP. V"ordsV from dual 'he value that can pass

to Lno cannot exceed digits

Describe 1racle database@s "h,sical and l#9ical str$ct$re ?

5ns6 Physical6 (ata 9les, Redo )og 9les, !ontrol 9le )ogical 6 'ales, :ie"s, 'alespaces,

etc

What is Chec< C#nstraintsB and with chec< #"ti#nsB and De%a$lt

0"ecicati#nB?

5ns6 !A8!Q Integrity !onstraints6 5 !A8!Q integrity constraint on a column or a set of

columns requires that a speci9ed condition e true or un#no"n 2ie 7ot false for every

ro" of the tale If a ($) statement is issued so that the condition of the !A8!Q

constraint evaluates to false, the statement is rolled ac# +ith chec# 3ption6 +ith

!hec# option restricts inserts and updates performed through the vie" to prevent them

from creating ro"s that the vie" cannot itself select ased on "here clause of the

create vie" statement ;or eg6 !reate or replace vie" +omen 5s select name from

8mployee +here SexM Z;emale1 +ith !hec# 3ption (efault Speci9cation It supplies a

default value if column value is not speci9ed on I7S8R' It can contain literals

2constants and SG) functions, US8R, SKS(5'8, sequence It cannot include references

to any columns

What is the ma+im$m n#. 1% c#l$mns a table can have ?

5ns6 *423racle

Can a tri99er written %#r a view ?

5ns6 7o


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!onsider a sequence "hose currval is & and gets incremented y & y using the nextval

reference "e get the next numer * Suppose at this point "e issue an rollac# and

again issue a nextval +hat "ill the output e ?

5ns6 -Can ,#$ create inde+ #n view ?

5ns6 7o

What is the diference between alias and s,n#n,m ?

5ns6 5lias is temporary and used "ith one query Synonym is permanent and not used

as alias

+hat1s the length of SG) integer ?

5ns6 -* it length

What is t


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tales are o"ned y SKS and their names all egin "ith :F\ :ie"s are created on these

tales, and then synonyms are created for the vie"s 'he synonym names egin "ith

:\

What is 0ave"#int ?5ns6 Savepoints are intermediate mar#ers that can e declared in long transactions that

contain many SG) statements By using savepoints, you can aritrarily mar# your "or#

at any point "ithin a long transaction 'his allo"s you the option of later rolling ac# all

"or# performed from the current point in the transaction to a declared savepoint "ithin

the transaction

+hat is (eadloc#s?

5ns6 5 deadloc# is a situation that can occur in multi@user systems that causes some

numer of transactions to e unale to continue "or# 5 deadloc# can occur "hen t"o

or more users are "aiting for data loc#ed y each other It typically happens "hen each

of t"o or more users are "aiting to access a resource that another user has already

loc#ed 'his creates a deadloc# situation ecause each user is "aiting for resources held

y the other user 8g 'ransaction & 'ime Point 'ransaction * UP(5'8 emp & UP(5'8

emp S8' sal M sal&& S8' sal M &-4* +A8R8 empno M &CCC +A8R8 empno M *CCC

UP(5'8 emp * UP(5'8 emp S8' sal M sal&& S8' sal M &-4* +A8R8 empno M *CCC

+A8R8 empno M &CCC 3R5@CCC0C - deadloc# detected "hile "aiting for resource

What is rivile9e ?

5ns6 5 privilege is a right to execute a particular type of SG) statement or to access

another user.s o=ect 'ypes of privileges 6 system privileges o=ect privileges

System Privileges 6 System privileges allo" users to perform a particular system"ide

action, or to perform a particular action on a particular type of o=ect 8g !reate

'alespace, (elete the ro" of any tale, etc 3=ect Privileges 6 3=ect privileges allo"

users to perform a particular action on a speci9c o=ect 8g (elete ro" of speci9c

tale, etc Roles 6 Roles are named groups of related privileges that are granted to users

or other roles 5dvantages of Roles 6 & Reduced granting of privileges * (ynamic

privilege management 2!hanging of privileges - Selective availaility of privileges

28nalling/(isaling roles 4 5pplication a"areness 28nalling/(isaling of roles y

application


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What is Tw# hase C#mmit ?

5ns6 '"o Phase !ommit is a mechanism "herein 3R5!)8 automatically controls and

monitors the commit or rollac# of a distriuted transaction and maintains the integrity

of the gloal dataase 'he Phases of the '"o@Phase !ommit $echanism 6 Prepare phase 6 'he gloal co@ordinator 2initiating node as#s participants to prepare

2to promise to commit or rollac# the transaction, even if there is a failure

!ommit phase 6 If all participants respond to the co@ordinator that they are prepared,

the co@ordinator as#s all nodes to commit the transaction if all participants cannot

prepare, the co@ordinator as#s all nodes to roll ac# the transaction

E+"lain ab#$t sna"sh#ts in detail?

5ns6 Snapshots are read@only copies of a master tale 2or multiple tales located on a

remote node 5 snapshot can e queried, ut not updated only the master tale can e

updated 5 snapshot is periodically refreshed to reect changes made to the master

tale 5 snapshot is a full copy of a tale or a suset of a tale that reects a recent

state of the master tale 5 snapshot is de9ned y a distriuted query that references

one or more master tales, vie", or other snapshots Simple vs !omplex Snapshots 6

8ach ro" in a simple snapshot is ased on a single ro" in a single remote tale

'herefore, a simple snapshot.s de9ning query has no ER3UP BK or !3778!' BK

clauses, or suqueries, =oins, or set operations If a snapshot.s de9ning query contains

any of these clauses or operations, it is referred to as a complex snapshot Internals of

Snapshot !reation6 +hen a snapshot is created, several operations are performed

internally y 3R5!)86 3R5!)8 2at the snapshot node creates a tale to store the ro"s

retrieved y the snapshot.s de9ning query this is the snapshot.s ase tale 3R5!)8

creates a read@only vie" on the S75P\ tale 2ase tale for queries issued against the

snapshot 3R5!)8 creates a second local vie" on the remote master tale It uses this

vie" "hen it refreshes the snapshot 5dditionally, if the snapshot is a simple snapshot,

3R5!)8 creates an index on the S75P\ tale 5ll of these internal o=ects are created in

the schema of the snapshot (o not alter, change data in, or delete these o=ects

manually

What is Re% C$rs#r?


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5ns6 5 R8; !URS3R is asically a data type 5 variale created ased on such a data

type is generally called a cursor variale 5 cursor variale can e associated "ith

di%erent queries at run@time 'he primary advantage of using cursor variales is their

capaility to pass result sets et"een su programs 2li#e stored procedures, functions,pac#ages etc

What is r#w chainin9 h#w d#es it ha""en?

5ns6 Ro" chaining occurs "hen a :5R!A5R* value is updated and the length of the ne"

value is longer than the old value and "on1t 9t in the remaining loc# space 'his results

in the ro" chaining to another loc# It can e reduced y setting the storage

parameters on the tale to appropriate values It can e corrected y export and import

of the e%ected tale

Describe hit rati# as it "ertains t# the database b$fers. What is the diference

between instantane#$s and c$m$lative hit rati# and which sh#$ld be $sed %#r

t$nin9?

5ns6 'he hit ratio is a measure of ho" many times the dataase "as ale to read a

value from the u%ers verses ho" many times it had to re@read a data value from the

dis#s 5 value greater than OC@[C< is good, less could indicate prolems If you simply

ta#e the ratio of existing parameters this "ill e a cumulative value since the dataase

started If you do a comparison et"een pairs of readings ased on some aritrary time

span, this is the instantaneous ratio for that time span 5n instantaneous reading gives

more valuale data since it "ill tell you "hat your instance is doing for the time it "as

generated over

What is a Cartesian "r#d$ct?

5ns6 5 !artesian product is the result of an unrestricted =oin of t"o or more tales 'he

result set of a three tale !artesian product "ill have x y > numer of ro"s "here x,

y, > correspond to the numer of ro"s in each tale involved in the =oin

What is a m$tatin9 table err#r and h#w can ,#$ 9et ar#$nd it?

5ns6 'his happens "ith triggers It occurs ecause the trigger is trying to update a ro" it

is currently using 'he usual 9x involves either use of vie"s or temporary tales so the

dataase is selecting from one "hile updating the other


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What are 08LC1DE and 08LERR and wh, are the, im"#rtant %#r L=08L

devel#"ers?

5ns6 SG)!3(8 returns the value of the error numer for the last error encountered 'he

SG)8RR$ returns the actual error message for the last error encountered 'hey can eused in exception handling to report, or, store in an error log tale, the error that

occurred in the code 'hese are especially useful for the +A87 3'A8RS exception

What are Transacti#nal Tri99ers ? ive the $ses #% Transati#nal Tri99er ?

5ns6 'ransactional 'riggers 9re in response to transaction processing events 'hese

events represent points during application processing at "hich 3racle ;orms needs to

interact "ith the data source 8xamples of such events include updating records, rolling

ac# to savepoints, and committing transactions By default, 3racle ;orms assumes that

the data source is an 3R5!)8 dataase, and issues the appropriate SG) statements to

optimi>e transaction processing accordingly Ao"ever, y de9ning

transactional triggers and user exits, you can uild a form to interact "ith virtually any

data source, including even non@relational dataases and at 9les !alling User 8xits

+hen you de9ne transactional triggers to interact "ith a non@3R5!)8 data source, you

"ill usually include a call to a user exit in the appropriate triggers 'he code in your user

exit interacts "ith the non@3R5!)8 data source 3nce the user exit has performed the

appropriate function 2as indicated y the trigger from "hich it "as called, it returns

control to 3racle ;orms for susequent processing ;or example, a user exit called from

an 3n@;etch trigger might e responsile for retrieving the appropriate numer of

records from the non@3R5!)8 data source 3nce the records are retrieved, 3racle ;orms

ta#es over the display and management of those records in the form interface, =ust as it

"ould if the records had een fetched from an 3R5!)8 dataase Uses for 'ransactional

'riggers 'ransactional triggers, except for the commit triggers, are primarily intended

to access certain data sources other than 3racle 'he logon and logo% transactional

triggers can also e used "ith 3racle dataases to change connections at run time

What is A$t#n#m#$s transacti#n ? Where d# we $se it?

5ns6 In 3racle.s dataase products, an autonomous transaction is an independent

transaction that is initiated y another transaction It must contain at least one

Structured Guery )anguage 2SG) statement 5utonomous transactions allo" a single


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transaction to e sudivided into multiple commit/rollac# transactions, each of "hich

"ill e trac#ed for auditing purposes +hen an autonomous transaction is called, the

original transaction 2calling transaction is temporarily suspended 'he autonomous

transaction must commit or roll ac# efore it returns control to the calling transaction3nce changes have een made y an autonomous transaction, those changes are

visile to other transactions in the dataase 5utonomous transactions can e nested

'hat is, an autonomous transaction can operate as a calling transaction, initiali>ing

other autonomous transactions "ithin itself

What is a "ac


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5ns6 'he L operator means that the P) SG) loc# requires user input for a variale 'he

LL operator means that the value of this variale should e the same as inputted y

the user previously for this same variale

If all the values from a cursor have een fetched and another fetch is issued, the output"ill e?

5ns6 )ast Record

+hat is a for"ard declaration ? +hat is its use ?

5ns6 P)/SG) requires that you declare an identi9er efore using it 'herefore, you must

declare a suprogram efore calling it 'his declaration at the start of a suprogram is

called for"ard declaration 5 for"ard declaration consists of a suprogram speci9cation

terminated y a semicolon

5ny three P)/SG) 8xceptions?

5ns6 'ooFmanyFro"s, 7oF(ataF;ound, :alueF8rror, ]eroF8rror, 3thers

Describe the $se #% FR1WTGE and FTGE in L=08L

5ns6


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process using the error@reporting functions SG)!3(8 and SG)8RR$ in an 3'A8RS

handler 'he statement RaiseF5pplicationF8rror can e called either from a procedure

ody or from an exception handler Irrespective of "hether an error occurred or not, a

raiseFapplicationFerror command al"ays raises an exception in the calling program 2ega forms trigger If an exception handler is not "ritten in that forms trigger, then a forms

error occurs

Q:To find the uniquness of the given record.

A1:select * from dual where 1=

(select max(count(empno)) from emp group by empno)

A2: select 1 yes_unique from emp

having count(distinct sal)=count(sal)

--> Q:To delete the even number of recordsA:delete from emp where rowid in(select rowid from

emp group by rownum,rowid having mod(rownum,2)0)

--> Q:To find the nth max sal

A1: select distinct sal from emp e where &n=

(select count(distinct sal) from emp d where e.sal Q:To find the nth min salA: select distinct sal from emp e where &n=

(select count(distinct sal) from emp d where e.sal>=d.sal)

--> Q:To select nth max sal from each department.

A1: select * from(select rownum r,e.* from

(select distinct sal from emp order by sal)e) where r=&n


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A2:select distinct sal from emp e where &n=

(select count(distinct sal) from emp d where e.sal Q:To select nth min sal from each department.

A: select distinct sal from emp e where &n=

(select count(distinct sal) from emp d where

e.sal>=d.sal and e.deptno=d.deptno)

--> Q:TO select top n salarys from each department.

A: select * from(select empno,ename,sal,deptno,rank() over

(partition by deptno order by sal desc) top_sal from emp)

where top_sal Q:To select bottom n salarys from each department

A:select * from(select empno,ename,sal,deptno,rank() over

(partition by deptno order by sal ) bottom_sal from emp)

where bottom_sal Q:To create the duplicate table without data

A: create table emp_dup as select * from emp where 1=2

--> Q:what will be the output

select * from emp where null is null

select * from emp where null=null

--> Q:To delete nth record

A:Delete from emp where rowid=(select rowid from emp group by

rowid,rownum having rownum=&n)

A2:delete from emp where rowid=(select max(r) from

(select rowid r from emp where rownum Q:To delete a record where there are no employes working

A:delete from(select * from dept e where not exists

(select 'x' from emp d where d.deptno=e.deptno))

--> Q:To display the duplicate records

A:select col1,col2,col# ,count(*) from table group by col1,col2,col# h

aving

count(*)>1

--> Q:To delete duplicate recoreds

A:delete from tabel a where rowid in

(select rowid from table b minus select max(rowid)

from table c group by c.col1,c.col2,c.col#)


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--> Q:To count the number of nulls and notnulls in Comm. column of emp

table

A:select count(decode(nvl2(comm,1,2),1,1)) nulls,

count(decode(nvl2(comm,1,2),2,1)) not_nulls from emp

--> Q:To select 1st and last record of the employee table

A: select * from(select rownum r,e.* from emp e)

where r=(select count(*) from emp) or r=1

--> Q:To count the number of sundays,mondays...saturdays..tot_days in

the current month

A:create table temp

(

num number(2)

)

insert into temp values(&num)

insert the values into temp from 1 to 31. and execute the below query

. select

count(decode(to_char(last_day(add_months(sysdate,-1))+num,'d'),1,1)) s

un,

count(decode(to_char(last_day(add_months(sysdate,-1))+num,'d'),2,1)) m

on,

count(decode(to_char(last_day(add_months(sysdate,-1))+num,'d'),3,1)

)tue,

count(decode(to_char(last_day(add_months(sysdate,-1))+num,'d'),4,1)

)wed,

count(decode(to_char(last_day(add_months(sysdate,-1))+num,'d'),5,1)) t

hu,

count(decode(to_char(last_day(add_months(sysdate,-1))+num,'d'),6,1)) fri,

count(decode(to_char(last_day(add_months(sysdate,-1))+num,'d'),7,1)) s

at,

to_char(last_day(sysdate),’dd’) tot_days

from temp where num Q:To select first and last record of employee table

A2: select * from emp where rowid in

(select rowid from emp group by rowid,rownum having rownum


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in(1,(select count(*) from emp)))

A3:select * from emp where rowid in

(select min(rowid) from emp union select max(rowid) from emp)

--> Q:To display the second max sal

A:select max(sal) from emp where sal Q:To display top n salarys

A:select * from(select rownum r,e.* from(select distinct sal from emp

order

by sal desc) e) where r Q:To select bottom n salarys

A:select * from(select rownum r,e.* from

(select distinct sal from emp order by sal ) e) where r Q:To select first and last salary of the table


(select distinct sal from emp order by sal desc ) e)

where r in(1,(select count(*) from emp))

--> Q:To select n to nth record

A:select * from(select rownum r,e.* from emp e)

where r between 4 and 7

--> Q:Display empno,ename,sal,max(sal) of their own dept ,max(SAL)

of the emp table of all the employes using with clause.

A:with maxsal as (select max(sal) max_sal from emp),dept_max as

(select deptno,max(sal) dept_maxsal from emp group by deptno)

select empno,ename,sal,(select max_sal from maxsal) maxsal,(select dep

t_maxsal from dept_max where

dept_maxsal.deptno=e.deptno) dept_max from emp e

--> Q:To find the empno,ename,deptno,maximum sal of the whole table,

maximum salary of the whole dept and minimum salary of the whole

department and dept name of the employee

A:select empno,ename,sal,deptno,(select max(sal) from emp) max_sal_ta

ble,

(select max(sal) from emp where deptno=e.deptno) dept_max,

(select min(sal) from emp where deptno=e.deptno) min_sal,

(select dname from dept

d where d.deptno=e.deptno) dname from emp e

--> Q:Display the employes whose salary is greater than his own

manager

A:select*from emp e where sal>(select sal from emp where empno=e.mgr)


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--> Q:Disply the employes whose sal is greater than the other managers

A: select * from emp e where sal> any(select sal from emp

where empno in(select distinct mgr from emp where mgre.mgr))

--> Q:To find the employes who are seniour to the employes who are

joined in the year 1981.

A:SELECT HIREDATE FROM EMP WHERE HIREDATE Q:To fined the employes who have joined on the same hiredate

A: SELECT * FROM EMP WHERE HIREDATE IN

(SELECT HIREDATE FROM EMP GROUP BY HIREDATE HAVING COUNT(HIREDAT

E)>1)

--> Q:To find the uniquness of the given column for the given table.

A: SELECT 1 YES_UNIQUE FROM DUAL

WHERE 1=(SELECT MAX(COUNT(EMPNO)) FROM EMP GROUP BY EMPNO)

--> Q:To delete the managers who are working under king with salary

ranging from 2000 to 3000 and joined in first half of 1981

A:DELETE FROM EMP_D WHERE EMPNO IN

(SELECT EMPNO FROM EMP_D WHERE EMPNO IN

(SELECT DISTINCT MGR FROM EMP_D WHERE MGR

(SELECT EMPNO FROM EMP_D WHERE

ENAME='KING')) AND MGR=(SELECT EMPNO FROM EMP_D WHERE EN

AME='KING'))

AND (SAL BETWEEN 2000 AND 3000) AND (HIREDATE BETWEEN '1-JAN-81' AND '31-MAY-81')

--> Q:To delete all the employes who have joined most recently under

king.

A: DELETE FROM EMP44 E WHERE MGR=(SELECT EMPNO FROM EMP44

D WHERE ENAME='KING' AND HIREDATE>E.HIREDATE)

--> Q:To delete all the grade 1 and grade 2 employes and woring in

chicago and joined in the first half of 81.

A: SELECT E.EMPNO,E.ENAME,S.GRADE,D.LOC,E.HIREDATE FROM SALGRADE

S, DEPT

D, EMP E WHERE E.DEPTNO=D.DEPTNO AND E.SALBETWEEN S.LOSAL AND S.HISAL

AND S.GRADE IN(1,2) AND D.LOC='CHICAGO'

AND E.HIREDATE BETWEEN '01-JAN-81' AND '30-JUN-81'

--> Q:To delete all the employes with experience 4


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AND JOB LIKE '%MAN')

--> Q:Delete all the employes of sales department whose salary ranging

from 1500 to 3000

A: DELETE FROM EMP44 WHERE EMPNO IN(select e.empno from emp44 e,dept

d where e.deptno=d.deptno

AND d.dname='SALES' AND E.SAL BETWEEN 1500 AND 3000)

--> Q:To delete all the grade 2 and 3 employes of sales dept and

working at chicago and joined after the all the employes whose

hiredate is in the year1980.

A:DELETE FROM EMP44 WHERE EMPNO IN(SELECT E.EMPNO FROM EMP44 E,DEPT

D,SALGRADE S

WHERE E.DEPTNO=D.DEPTNO

AND E.SAL BETWEEN S.LOSAL AND S.HISAL

AND S.GRADE IN(2,3)

AND D.DNAME ='SALES'

AND D.LOC='CHICAGO'AND

HIREDATE>ALL(SELECT HIREDATE FROM EMP44 WHERE HIREDATE LIKE'%80'))

--> Q: Delete the emps whose salary is lowest salary of their own

deptartment

A: DELETE FROM EMP44 WHERE EMPNO IN

(SELECT EMPNO FROM EMP44 WHERE SAL IN

(SELECT MIN(SAL)

FROM EMP44 GROUP BY DEPTNO))

A2.delete from emp e where sal =(select min(sal) from emp

d where d.deptno=e.deptno)

--> Q: To find the employes who are seniour to their own managers.

A: SELECT * FROM EMP E WHERE HIREDATE<

(SELECT HIREDATE FROM EMP WHERE EMPNO=E.MGR)

--> Q:To find the employes who are seniour to their own managers using

corelated sub query.

A: DELETE FROM EMP44 WHERE EMPNO IN

(SELECT E.EMPNO FROM EMP44 E WHERE

HIREDATE Q:To find the employes who are seniour to their own manager using

self join.

A: SELECT E.* FROM EMP E,EMP

D WHERE E.MGR=D.EMPNO AND E.HIREDATE Q: Delete the employes whose experience greater than four.

A: delete from emp where hiredate in(select hiredate from emp where (m

onths_between(sysdate,hiredate)/12)>4)


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--> Q: To list the employes whose salary is less than his own manages

and greater than any of the other managers.

A: select * from emp e where sal any(select sal from emp

where empno in(select distinct mgr from emp where mgre.mgr))

--> Q:To display the employee name and this manager name for each

record selected.

A: SELECT E.EMPNO,E.ENAME,D.ENAME MGR_NAME FROM EMP E,EMP

D WHERE D.EMPNO=E.MGR

--> Q:To display all the employes who are working under blake and

display the manager name along with the select list.

A: SELECT * FROM(SELECT E.*,D.ENAME MGR_NAME FROM EMP E,EMP

D WHERE E.MGR=D.EMPNO ) WHERE MGR_NAME='BLAKE'

--> Q:To find the employes who are seniour to all the other managers.

A:SELECT * FROM EMP E WHERE HIREDATE Q:To count the m's and f's from the column and display in the same

row like

A:SELECT COUNT(DECODE(GENDER1,'M',1)) M, COUNT(DECODE(GENDER1,'F',1))

F FROM GENDER

--> Q:To find the emps who are senior to his own manager and junior toany one of the other managers

A: select * from emp e where hiredate any(SELECTHIREDate from emp where empno

IN(SELECT DISTINCT MGR FROM EMP

WHERE MGR (SELECT EMPNO FROM EMP WHERE EMPNO=E.MGR)))

--> Q:To convert the given number into string format.

A:SELECT TO_CHAR(TO_DATE(SAL,'J'),'JSP') SAL_STRING,SAL FROM EMP

Q:To find the employes who have joined on the same hiredate.

A: select*from emp where hiredate in(select hiredate from(select hired

ate, count(hiredate) from emp group by hiredate

having count(*)>1))

--> Q:To delete nth record.

A: delete from emp44 where rowid=(select rowid from emp44 group by row

id,rownum having rownum=&n)

--> Q:To find the uniqueness of any given cloumn in a given table.

A: SELECT CASE


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WHEN COUNT( DISTINCT &COLUMN)=COUNT(*)

THEN

'YES_UNIQUE'

ELSE

'NOT_UNIQUE'

END CASE

FROM &TABLE

--> Q:To find nth minimum salary.


(select distinct(sal) from emp order by sal)e)where r=&n

--> Q:To find nth minimum salary.

A: select * from(select rownum r,e.* from

(select distinct(sal) from emp order by sal)e)where r=&n

--> Q:To delete the duplicate records existing.

A: delete from emp_dups e where rowid Q:To count the number of nulls and notnulls.

A:SELECT COUNT(*)-COUNT(DECODE(NVL(COMM,1),1,1)) NOT_NULLS,

COUNT(DECODE(NVL(COMM,1),1,1)) NULLS FROM EMP

--> Q:To select the duplicate records.

A: select e.* from emp_dups e where rowid Q:To find the hirearchey of the employee table

A; select level, e.* from emp e connect by prior empno=mgr start

with mgr is null

--> Q: To incrimentally update the employee table from nth row

A: update emp set empno=rownum+999 where rowid >

(select max(rowid) from emp where

rownum Q: To incrementally update the table where mgr is null

A: update emp set empno=rownum where rowid in

(select rowid from emp where comm is null)

--> Q:To select from nth record to nth record.

A: select * from(select rownum r,e.* from emp e)


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where r between &n and &m

--> Q:To select the given records

A:select * from(select rownum r,e.* from emp e)

where r in(3,5,6)

--> Q:TO delete the nth record

A:delete from emp where rowid=

(select rowid from emp group by rownum,rowid

having rownum=&n )

--> Q:TO delete the given set of records

A:delete from emp where rowid in

(select rowid from emp group by rownum,rowid

having rownum in (4,5,6) )

pl/sql interview q

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