PL SQL Packages and Triggers

8/10/2019 PL SQL Packages and Triggers

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+ #od!

4ere is the #asic s!ntax for a package speci&cation'

The 567(T7 P(58(97 ke!words are "sed to create the package speci&cation'

(nd the -owning- schema is speci&ed along with the package name*

schema'package:name

;"ltiple p"#lic o#$ects s"ch as f"nctions and proced"res can #e declared'

( "ser can call a p"#lic packaged o#$ect provided he or she has 7


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( package #od! consists of the exec"ta#le code for packaged o#$ects'

P"#lic and private o#$ects are coded in the same wa! in the package #od!'

"t an o#$ect coded in the package #od! is p"#lic if it is declared in the package

speci&cation'

(n application developer m"st have 567(T7 P6%573U67 privilege on the data#ase

to create a p"#lic package'

,o"r 3( can grant the necessar! privilege'

Let=s look at an example package called enroll:new'

4ere is the package speci&cation'

The package is named enroll:new and is owned #! the admission schema'

Two p"#lic proced"res are declared* charge:st" and grade:new'

( package speci&cation is created separatel! from the package #od! #! "sing a

script &le or #! entering the code interactivel! at the SQL> prompt'

,o" can examine package so"rce code and s!ntax errors #! 2"er!ing the

"ser:so"rce and "ser:error views of the owning schema'

4ere is the code for the example package #od!'


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Two proced"res are coded'

(nd #eca"se #oth proced"res were declared in the package speci&cation) the! are

p"#lic package o#$ects'

0hen the script containing the package #od! is created) the packaged proced"res

admission'enroll:new'charge:st" and admission'enroll:new'grade:new can #e called

#! an! application tool in the %racle environment'

3ot notation m"st #e "sed to access a packaged o#$ect*

schema:name'package:name'o#$ect:name

This is how a packaged o#$ect is exec"ted at the SQL> prompt'


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This is how a packaged o#$ect is called from within a PL/SQL #lock or s"#program'

The ke!word 7


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( package #od! is not needed #eca"se all the package contents are datat!pes'

%nce the package has #een created and stored in the data#ase) instances of the

"serde&ned datat!pes can #e declared in an! application'

4ere is an example PL/SQL #lock that declares an instance of the st"dent:record

datat!pe'

It is not necessar! to recode a T,P7 declaration in the calling program'

%racle will o#tain the T,P7 declaration for the "serde&ned datat!pe app:record

from the packaged o#$ect appdev'records'st"dent:record'


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The owning schema of the packaged o#$ect is appdev'

The package name is records'

(nd the packaged o#$ect name is st"dent:record'

,o" can pass an instance of a "serde&ned 675%63 or T(L7 datat!pe into apackaged s"#program as an act"al parameter'

.or example) in a calling program !o" can declare an instance of a "serde&ned

675%63 datat!pe #! calling a packed o#$ect that contains the T,P7 declaration'

(nd then pop"late and pass the 675%63 &elds into another packaged proced"re as

act"al parameters'

The called packaged proced"re appdev'maintain can also declare an instance of the

"serde&ned 675%63 #! calling the appdev'records package'

The important point to remem#er is that !o" can "se a package to contain a data

str"ct"re declaration'

(nd !o" can re"se that data str"ct"re an!where in the %racle environment witho"t

having to recode the declaration'

,o" can pass an instance of a "serde&ned 675%63 or T(L7 datat!pe into a

packaged s"#program as an act"al parameter'

.or example) in a calling program !o" can declare an instance of a "serde&ned

675%63 datat!pe #! calling a packed o#$ect that contains the T,P7 declaration'

(nd then pop"late and pass the 675%63 &elds into another packaged proced"re as

act"al parameters'


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The called packaged proced"re appdev'maintain can also declare an instance of the

"serde&ned 675%63 #! calling the appdev'records package'

The important point to remem#er is that !o" can "se a package to contain a data

str"ct"re declaration'

(nd !o" can re"se that data str"ct"re an!where in the %racle environment witho"t

having to recode the declaration'

%racle allows the same s"#program name to #e "sed for more than one PL/SQL

packaged s"#program) provided the formal parameters are di@erent'

This concept is called overloading'

%verloading can #e "sed to allow a single call to access m"ltiple f"nctions andproced"res'

.or example) a PL/SQL package can contain a proced"re that accepts a A(654(6B

formal parameter'

(nd the same package can contain a second proced"re of the same name that

accepts a NU;76 formal parameter'

%racle resolves overloading #! comparing the act"al parameters s"pplied at r"n

time with the formal parameters declared in the packaged s"#programs'

4ere is an example package that contains two proced"res called del:st"'


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If del:st" is called and has passed a A(654(6B parameter) the &rst proced"re will

exec"te'

(nd if del:st" is passed a NU;76 parameter) the second proced"re will exec"te'

%verloading works onl! if the formal parameters in each s"#program di@er inn"m#er) order) or datat!pe'

S"#t!pes of datat!pe NU;76 are not considered di@erent for the p"rpose of

overloading s"#program names'

%racleC "ses a package called standard to de&ne the PL/SQL environment'

The standard package declares datat!pes) exceptions) f"nctions) and proced"res'

(ll declarations in the standard package are p"#lic and are glo#all! visi#le to all

applications and "sers'

This means that an! o#$ect declared in the standard package is availa#le to an! tool

in the %racle environment that s"pports PL/SQL'

.or example) the no:data:fo"nd exception is declared in the standard package'

(nd it can #e "sed #! an! PL/SQL program'


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SQLDPl"s f"nctions s"ch as T%:NU;76 and 375%37 are also declared in the

standard package'

The standard package is created #! the 3( #! r"nning a script &le called

standard's2l'

The script that creates the standard package is "s"all! stored in the

EoracleErd#msEadmin director!'

%nce it is created) the standard package is stored in parsed format in the data#ase'

The standard package is like an! other stored PL/SQL package'

0hen a "ser calls a packaged o#$ect) the package is loaded and held -resident- in

memor!'

(nother "ser can "se an o#$ect in the package witho"t ca"sing disk I/%'

4ere is an extract from the script "sed to create the standard package'

e caref"l not to declare a f"nction or proced"re with the same name as an o#$ect

in the standard package'


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If !o" do) the local declaration will override the glo#al declaration and the core

f"nctionalit! of PL/SQL ma! #e a@ected'

( n"m#er of other packages are also s"pplied with %racleC'

These packages contain proced"res and f"nctions that can assist the eFcient

development and administration of the data#ase'

The d#ms:o"tp"t package is partic"larl! "sef"l in de#"gging applications'

.or example) !o" can o"tp"t varia#le val"es to screen'

The package d#ms:o"tp"t is created #! exec"ting the script d#msopt's2l'

UNIT B

,o" will now develop a sample PL/SQL package and calling program'

4ere is the speci&cation for the sample package and calling program'

To #egin) let=s examine what the package and calling program sho"ld do logicall!'

The package sho"ld contain a p"#lic f"nction that accepts a 675%63 datat!pe as a

formal parameter and inserts a new row in the st"dent ta#le'

(nd the f"nction sho"ld ret"rn a val"e to the calling program to indicate whether a

row was s"ccessf"ll! inserted'

The package sho"ld also contain a p"#lic proced"re that accepts a social sec"rit!

n"m#er as a parameter and deletes a row from the st"dent ta#le'


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(nd &nall!) the calling program sho"ld call and pass parameters to the packaged

f"nction to create a new st"dent'

That=s what the program sho"ld do logicall!'

The next step is to code the package speci&cation'

The speci&cation sho"ld declare the f"nction and proced"re as p"#lic packaged

o#$ects'

6emem#er) a calling program has access onl! to p"#lic packaged o#$ects declared

in the package speci&cation'

To #egin the speci&cation) a 567(T7 statement sho"ld #e coded'

Next) a 675%63 datat!pe is declared to hold the st"dent details'

It is not necessar! to declare an instance of this 675%63 in the package

speci&cation'

%nce the package is created) instances can #e declared #! an! calling PL/SQL

program'

Next) the f"nction to create a st"dent is declared'

The 567(T7 ke!word is not needed within the package'

(n instance of the 675%63 datat!pe sho"ld #e declared as a formal parameter in

the f"nction'

The 67TU6N cla"se speci&es that a NU;76 datat!pe is ret"rned to the calling

program'


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.inall!) the proced"re to delete a st"dent is declared'

( formal IN parameter is speci&ed in the proced"re declaration'

That=s the end of the package speci&cation'

The script is exec"ted to create and store the package speci&cation in the data#ase'

The next step is to code the package #od! to contain the exec"ta#le code for the

packaged f"nction and proced"re'

.irst) the 567(T7 statement sho"ld #e coded'

Next) the f"nction speci&cation is coded'


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(nd the f"nction #od! is coded'

Next) the proced"re speci&cation is coded'

(nd &nall!) the proced"re #od! is coded'

That=s the end of the package #od!'


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The next step is to code the calling program'

.irst) an instance of the packaged datat!pe is declared'

3ot notation is "sed to reference the packaged o#$ect'

Statements are coded to prompt the "ser to enter r"ntime val"es'


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Next) an I. statement sho"ld #e coded to call the f"nction and pass in the act"al

parameters'

That=s the end of the calling program'

Let=s examine what happens when the calling program is exec"ted'

.irst) a data str"ct"re called local:record is created in memor! "sing the T,P7

declaration contained in the packaged o#$ect appdev'st"dents'st"dent:row'

Next) the "ser is prompted to pop"late local:record with r"ntime val"es'

The packaged f"nction appdev'st"dents'inp"t:rec is called and passed local:record

as an act"al parameter'

The calling program is temporaril! s"spended'

(nd %racle #egins exec"ting the p"#lic packaged f"nctionappdev'st"dents'inp"t:rec'

.irst) the act"al parameter local:record is accepted into the formal parameter

st"dent:record'

The parameter st"dent:record is an instance of the "serde&ned datat!pe

st"dent:row'

st"dent:row was declared as a p"#lic packaged o#$ect in the package speci&cation'

Next) the INS76T statement creates a new row in the #ase ta#le st"dent'

If the insert is s"ccessf"l) the 67TU6N statement ret"rns a val"e of 1 to the calling

program'

If the "pdate failed for an! reason) the exception handler ret"rns a val"e of G to the

calling program'

The packaged f"nction &nishes exec"ting when the ret"rn statement is exec"ted'


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"t the package is still resident in memor!'

(nd an! "ser can call an! o#$ect in the package witho"t ca"sing disk I/%'

The calling program res"mes exec"ting and eval"ates the ret"rn val"e received

from the packaged f"nction'

(nd a s"ita#le message is o"tp"t to screen'

4ere is the r"ntime o"tp"t generated if the insert was carried o"t s"ccessf"ll!'

Look at how PL/SQL s"#stit"tes the r"ntime val"es entered #! the "ser for the

declared s"#stit"tion varia#les'

This sort of feed#ack can #e "sef"l in de#"gging an application'

"t end"sers sho"ld alwa!s #e -shielded- from "nfriendl! messages #! "sing front

end application development tools s"ch as 3eveloper/BGGG .orms'

Interface design is examined in detail in the 5T S!stems co"rse 3eveloper/BGGG

.orms* ."ndamentals'


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PL/SQL s"pports a stored program "nit called a data#ase trigger'

This is stored as a PL/SQL proced"re in the data#ase and is associated with a named

data#ase ta#le'

( data#ase trigger cannot #e associated with a view'

( data#ase trigger is like a stored f"nction or proced"re'

It consists of PL/SQL and SQLDPl"s code'

It can call and pass parameters to a packaged PL/SQL proced"re or f"nction'

4owever) it cannot #e called or exec"ted #! a "ser or application program'

( data#ase trigger is independent of "sers and applications'

( data#ase trigger is exec"ted or &red a"tomaticall! #! %racle when prede&ned

SQLDPl"s 3;L Hdata manip"lation lang"age statements are exec"ted on theassociated #ase ta#le'

This means that a trigger can &re onl! when one or more of these 3;L statements

are exec"ted*

+ INS76T

+ UP3(T7

+ 37L7T7

( data#ase trigger cannot &re when a S7L75T statement is exec"ted'

( data#ase trigger sho"ld not #e conf"sed with a 3eveloper/BGGG .orms trigger' The

role of a trigger in the 3eveloper/BGGG .orms environment is examined in the 5T

S!stems co"rse 3eveloper/BGGG .orms* ."ndamentals'

3ata#ase triggers can help protect the integrit! of the data#ase in several wa!s'

( data#ase trigger can carr! o"t complex validation to enforce #"siness r"les'

.or example) it can &re to prevent an application from inserting data that does not

meet prede&ned criteria'

( data#ase trigger can #e "sed to carr! o"t event logging'

.or example) in a transaction processing environment) it can insert data a#o"t 3;L

operations in an event log ta#le'

( data#ase trigger can help the 3( to control 3;L operations'


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,o" m"st #e granted the appropriate privilege #! the 3( to s"ccessf"ll! create a

data#ase trigger'

The privilege 567(T7 T6I9976 allows !o" to create a trigger in !o"r schema'

(nd 567(T7 (N, T6I9976 allows !o" to create a trigger in another schema'

( "ser or application does not re2"ire privileges on a data#ase trigger or on an!

ta#les accessed #! a trigger'

The privileges of the schema that -owns- the trigger are implicitl! granted for the

d"ration of the exec"tion of the trigger'

( trigger can &re #efore or after a 3;L operation'

( 7.%67 trigger is &red #efore the triggering 3;L statement is exec"ted'

So) it can #e "sed to determine whether to a#ort the triggering statement'

It can also #e "sed to derive val"es #efore an INS76T or UP3(T7 statement is

exec"ted'

(n (.T76 trigger is &red after the triggering 3;L statement has exec"ted'

It can #e "sed to enforce integrit! constraints or log 3;L activit!'

( trigger can &re on INS76T) UP3(T7) or 37L7T7 statements'

(nd a trigger can &re at 6%0 level or at ST(T7;7NT level'

In all) there are twelve possi#le triggering events for each ta#le'


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So) !o" can create a maxim"m of twelve triggers on an! ta#le'

In releases of %racle prior to C'1) !o" cannot create more than one trigger t!pe per

ta#le'

4ere is the #asic algorithm that %racle "ses when &ring stored data#ase triggers'

( data#ase trigger is a failsafe mechanism to protect data integrit!'

( trigger is not a s"#stit"tion for proper ta#le de&nition or ade2"ate sec"rit! and

data validation techni2"es'

6eferential integrit! constraints sho"ld contin"e to #e incl"ded in the 567(T7 T(L7statement'

In fact) a trigger cannot override constraints or change data in a constraining ta#le

referenced in the triggering statement'

( ta#le is constrained if it de&nes a foreign ke! relationship with another ta#le'


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Sec"rit! and data validation sho"ld #e implemented in the frontend application

#efore #ase ta#le data manip"lation is attempted'

(n exception raised in a trigger sho"ld #e handled at trigger level #! coding an

exception section in the trigger #od!'

(n "nhandled exception will ca"se a complete roll#ack of the triggering statement'

eca"se data#ase triggers ca"se a performance overhead) the! sho"ld #e "sed

with discretion'

It is the responsi#ilit! of the 3( to develop a comprehensive strateg! for the

enforcement of data integrit! r"les'

(nd it is the responsi#ilit! of application developers to ens"re that programs are

-triggeraware-'

( data#ase trigger has some limitations'

( data#ase trigger cannot iss"e a S7L75T statement to a ta#le that is m"tating'

( #ase ta#le that is in the process of changing is said to #e m"tating'

.or example) a trigger that is in the process of &ring cannot read from the ta#le it is

&ring on'

(ltho"gh !o" can "se SQLDPl"s 3;L statements in a trigger) !o" cannot "se 33L or

35L statements'

.or example) statements s"ch as 567(T7 T(L7 and 96(NT S7L75T are nots"pported in a data#ase trigger'

(nd !o" cannot "se %racle=s transaction processing options* 5%;;IT) 6%LL(58)

and S(A7P%INT'

%racle s"pports a ST(T7;7NT data#ase trigger that &res once when a triggering

3;L statement is exec"ted'

( ST(T7;7NT trigger can #e speci&ed to &re #efore or after an INS76T) UP3(T7) or

37L7T7 statement'

4ere is an example 7.%67 INS76T ST(T7;7NT trigger'


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ST(T7;7NT is the defa"lt trigger t!pe'

( 567(T7 T6I9976 statement is "sed to create and name the ST(T7;7NT trigger'

The trigger will &re when the event -7.%67 INS76T %N st"dent- occ"rs'

( trigger restriction cannot #e coded in a ST(T7;7NT trigger'

The I. statement in the example trigger #od! tests whether %racle=s internal date

S,S3(T7 is greater than =J(N1K='

(nd if it is) the trigger is forced to fail and the triggering 3;L statement is a#orted'

The example trigger code is saved as a script and exec"ted at the SQL> prompt to

create and store the trigger in the data#ase'

4ere is the feed#ack generated when the example ST(T7;7NT trigger is ca"sed to

&re #! an INS76T statement on the st"dent ta#le'

4ere is an example of an (.T76 37L7T7 ST(T7;7NT trigger'


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The ke!words .%6 7(54 6%0 specif! that the trigger &res for each row a@ected #!

the triggering event'

6emem#er) %racle creates a ST(T7;7NT trigger #! defa"lt if the ke!words .%6

7(54 6%0 are omitted'

The trigger #od! I. statement will insert a row in the de#ts:o"tstanding ta#le after

each row is deleted) provided the deleted loan:amo"nt is greater than ?ero'

Look again at the I. statement condition in the example 6%0 trigger'

This code "ses a notation called a correlation name'

It can #e "sed in a 6%0 trigger to reference a data element that is in the process of

m"tating'

In this case) the correlation name %L3 references data in a row that has $"st #een

logicall! deleted #! the triggering statement'

(nd loan:amo"nt references the #ase ta#le col"mn in the -deleted- row'

( correlation name is preceded #! a colon H*) "nless it is "sed in a trigger

restriction'

,o" can reference a deleted row in a trigger "sing the correlation name %L3

#eca"se the deletion has not !et #een committed to the data#ase'

Think a#o"t what happens at r"ntime'

This statement ca"ses all the rows in the st"dent ta#le to #e deleted'


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(nd after each row is deleted) the example trigger &res once'

If the val"e of *%L3'loan:amo"nt in the logicall! deleted row is greater than ?ero)

the trigger inserts a row in the de#ts:o"tstanding ta#le'

In an INS76T 6%0 trigger there is no old val"e) #"t !o" can "se the N70 correlation

name to refer to an inserted data element* *N70'col"mn:name

In an UP3(T7 6%0 trigger !o" can "se #oth the %L3 and N70 correlation names to

compare data val"es #efore and after the "pdate) for example I.

H*%L3'col"mn:name > *N70'col"mn:name T47N'''

In a 37L7T7 6%0 trigger) there is no new val"e) so onl! the %L3 correlation name

can #e "sed'

%racle does not s"pport correlation names in a ST(T7;7NT trigger'

%racle allows the defa"lt correlation names to #e renamed "sing this s!ntax in the6%0 trigger event* 67.767N5IN9 MN70 %L3O (S 67.767N57:N(;7

4ere is an example of a trigger that "ses referencing to -rename- the correlation

names %L3 and N70'

This techni2"e can #e "sed to avoid potential naming conicts'

( trigger restriction can #e "sed in a 6%0 trigger to determine whether to exec"te

the trigger #od! for each row a@ected #! the triggering statement'

4ere is the s!ntax for a 6%0 trigger restriction'

The trigger condition can #e an! valid #oolean PL/SQL expression) #"t cannot

incl"de a 2"er!'

Look now at this example (.T76 UP3(T7 6%0 trigger that "ses a restriction'


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( colon is not "sed with a correlation name in a 6%0 trigger restriction'

The trigger restriction is eval"ated for each row a@ected #! the 3;L statement'

If the restriction eval"ates to T6U7) the trigger #od! is exec"ted and a row isinserted in the refer:de#t:collector ta#le'

(nd if the restriction eval"ates to .(LS7) the next row is considered'

( ST(T7;7NT trigger does not s"pport restriction'

Look again at the example trigger event'

The loan:amo"nt col"mn in the st"dent ta#le has #een speci&ed in the trigger

event'

This means that the trigger will &re onl! if data in that col"mn is a@ected #! anUP3(T7 statement'

,o" can specif! more than one #ase ta#le col"mn in an UP3(T7 trigger event'

If !o" omit a col"mn reference) the trigger will &re when an! col"mn in the ta#le is

a@ected #! a triggering 3;L statement'


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%racle allows the "se of the following conditional predicates in a ST(T7;7NT or

6%0 trigger that has more than one triggering event*

+ I. INS76TIN9 T47N'''

+ I. UP3(TIN9 T47N'''

+ I. 37L7TIN9 T47N'''

This means that !o" can "se a di@erent set of trigger #od! statements for each

trigger event'

This is the #asic s!ntax "sed in a trigger #od! to identif! the triggering event and

exec"te the related statements'

Predicates can #e com#ined* I. HINS76TIN9 %6 UP3(TIN9 T47N'''

4ere is an example trigger that "ses conditional predicates to determine which set

of trigger #od! statements sho"ld #e exec"ted'

The trigger event speci&es that the trigger will &re #efore an INS76T) UP3(T7) or

37L7T7 statement is exec"ted on the st"dent ta#le'


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The conditional predicates are "sed to identif! the triggering event'

0hen the trigger is ca"sed to &re #! an INS76T or UP3(T7 statement) the &rst set of

statements are exec"ted'

The f"nction INIT5(P is "sed to ens"re that st"dent names are inserted into the

#ase ta#le in the correct case'

0hen the trigger is ca"sed to &re #! a 37L7T7 statement) a row is inserted in the

st"dent:archive ta#le'

,o" can also "se the conditional predicate to identif! whether a speci&c #ase ta#le

col"mn has #een a@ected #! a triggering 3;L statement'

3ata#ase performance can #e a@ected #! the extra processing overhead generated

#! a data#ase trigger'

Performance can #e a partic"lar pro#lem if a trigger is complex or if a large amo"nt

of data is loaded at once'

In fact) it ma! #e expedient to temporaril! disa#le a data#ase trigger #efore

carr!ing o"t #"lk loading of data'

The %racle "tilit! SQLDLoader can #e "sed to #"lkload data'

,o" can disa#le all triggers on a ta#le'

%r !o" can disa#le an individ"al trigger'


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If !o" decide to disa#le a #ase ta#le trigger for the d"ration of a data load) it is

important that another method is "sed to validate the data'

The 3( onl! sho"ld decide whether a trigger sho"ld #e disa#led'

Triggers on a ta#le can #e reena#led "sing the 7N(L7 ke!word'

(nd a trigger can also #e reena#led individ"all!'

,o" can delete a trigger from the data#ase "sing this s!ntax* 36%P T6I9976

trigger:name

0hen a trigger is created) the so"rce code is stored in the data#ase'

,o" can examine so"rce code and other trigger details #! 2"er!ing these defa"lt

views*

+ "ser:triggers

+ d#a:triggers

+ all:triggers

4ere is the data de&nition of the "ser:triggers view'


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This S7L75T statement retrieves information on the triggers in the active schema'

The 3( can examine details of an! trigger #! "sing the views d#a:triggers and

all:triggers'

UNIT R

,o" will now develop a sample data#ase trigger'

The trigger sho"ld insert a row in the grade:trans:log ta#le whenever a row is

deleted from the grade ta#le'

The p"rpose of this trigger is to maintain a transaction log'

The sample trigger sho"ld #e created on the grade ta#le'

The most appropriate trigger to "se here is an (.T76 37L7T7 6%0 trigger'

(n (.T76 trigger is generall! more eFcient than a 7.%67 trigger #eca"se a single

data#ase call is generated'

( 6%0 trigger is generall! more "sef"l than a ST(T7;7NT trigger #eca"se it can &re

once for each row a@ected #! the triggering statement'


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The &rst step in creating the sample trigger is to name the trigger grade:trigger'

Next) a trigger event sho"ld #e coded'

The trigger will &re when the event -after delete on grade- occ"rs'

The trigger sho"ld &re once after each row is deleted'

The ke!words .%6 7(54 6%0 specif! that the trigger is a 6%0 trigger that will &re

once after each row is deleted'

The next step in coding the sample trigger is the trigger #od!'

(n INS76T statement is coded to create a new row in the grade:trans:log ta#le after

each deletion from the grade ta#le'

5orrelation names sho"ld #e "sed in the A(LU7S cla"se of the INS76T statement to

reference each row as it is deleted from the grade ta#le'

The correlation name %L3 refers to the row that has $"st #een logicall! deleted #!

the triggering statement'

The trigger is now completed'


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The trigger code can #e saved as a script and exec"ted at the SQL> prompt to

create and store the trigger in the data#ase'

This SQL statement ca"ses fo"r rows to #e deleted from the grade ta#le'

The triggering statement deletes fo"r rows and ca"ses the trigger event -after

delete on grade-'

So the trigger is &red fo"r times) once for each row a@ected #! the triggering

statement'

( S7L75T statement on the grade:trans:log ta#le veri&es that the trigger &red

s"ccessf"ll!'


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Documents

PL SQL Packages and Triggers