Обсуждение: Trigger function to know which fields are being updated
I am writing a trigger function. How can I know which fields are being updated in the PL/SQL function? For example I have a table here: CREATE TABLE COMPANY ( COMPANY_ID VARCHAR(10) NOT NULL, NAME VARCHAR(30), ADDRESS VARCHAR(30)); I want to write a trigger to block all update statements without updating NAME. I tried the following code block and it doesn't work: IF TG_OP = ''UPDATE'' THEN IF NEW.NAME IS NULL THEN RAISE NOTICE ''Field NAME must be provided!''; END IF; ENDIF; Are there any functions like the Oracle's UPDATING() predicate? Bernard Cheung _________________________________________________________________ Linguaphone : Learning English? Get Japanese lessons for FREE http://go.msnserver.com/HK/46165.asp
--- Bernard Cheung <cheungsw@hotmail.com> wrote: > I am writing a trigger function. How can I know > which fields are being > updated in the PL/SQL function? > > For example I have a table here: > > > CREATE TABLE COMPANY ( > COMPANY_ID VARCHAR(10) NOT NULL, > NAME VARCHAR(30), > ADDRESS VARCHAR(30)); > > I want to write a trigger to block all update > statements without updating > NAME. I tried the following code block and it > doesn't work: > > > IF TG_OP = ''UPDATE'' THEN > IF NEW.NAME IS NULL THEN > RAISE NOTICE ''Field NAME must be > provided!''; > END IF; > END IF; That should work. Perhaps "name" is not actually null, but rather an empty string? In that case, your test needs to be: "IF NEW.NAME IS NULL OR NEW.NAME = '''' THEN..." > > Are there any functions like the Oracle's UPDATING() > predicate? > > Bernard Cheung > > _________________________________________________________________ > Linguaphone : Learning English? Get Japanese > lessons for FREE > http://go.msnserver.com/HK/46165.asp > > > ---------------------------(end of > broadcast)--------------------------- > TIP 1: subscribe and unsubscribe commands go to majordomo@postgresql.org __________________________________ Do you Yahoo!? Win a $20,000 Career Makeover at Yahoo! HotJobs http://hotjobs.sweepstakes.yahoo.com/careermakeover
Thank you, but my intension is to check whether the user supplies NAME when updating the record. For example the trigger shall allow statement 1 and block statement 2: 1. UPDATE COMPANY SET NAME = 'ABC', ADDRESS = '123 Drive' WHERE COMPANY_ID = 1; 2. UPDATE COMPANY SET ADDRESS = '123 Drive' WHERE COMPANY_ID = 1; I want the trigger to ensure that the user must provide value for NAME when updating this record. >From: Jeff Eckermann <jeff_eckermann@yahoo.com> >To: Bernard Cheung <cheungsw@hotmail.com>, pgsql-sql@postgresql.org >Subject: Re: [SQL] Trigger function to know which fields are being updated >Date: Mon, 10 May 2004 14:38:56 -0700 (PDT) > > >--- Bernard Cheung <cheungsw@hotmail.com> wrote: > > I am writing a trigger function. How can I know > > which fields are being > > updated in the PL/SQL function? > > > > For example I have a table here: > > > > > > CREATE TABLE COMPANY ( > > COMPANY_ID VARCHAR(10) NOT NULL, > > NAME VARCHAR(30), > > ADDRESS VARCHAR(30)); > > > > I want to write a trigger to block all update > > statements without updating > > NAME. I tried the following code block and it > > doesn't work: > > > > > > IF TG_OP = ''UPDATE'' THEN > > IF NEW.NAME IS NULL THEN > > RAISE NOTICE ''Field NAME must be > > provided!''; > > END IF; > > END IF; > >That should work. Perhaps "name" is not actually >null, but rather an empty string? In that case, your >test needs to be: "IF NEW.NAME IS NULL OR NEW.NAME = >'''' THEN..." > > > > > Are there any functions like the Oracle's UPDATING() > > predicate? > > > > Bernard Cheung > > > > ---------------------------(end of > > broadcast)--------------------------- > > TIP 1: subscribe and unsubscribe commands go to >majordomo@postgresql.org _________________________________________________________________ Linguaphone : Learning English? Get Japanese lessons for FREE http://go.msnserver.com/HK/46165.asp
--- Bernard Cheung <cheungsw@hotmail.com> wrote: > Thank you, but my intension is to check whether the > user supplies NAME when > updating the record. > > For example the trigger shall allow statement 1 and > block statement 2: > > 1. UPDATE COMPANY SET NAME = 'ABC', ADDRESS = '123 > Drive' WHERE COMPANY_ID = > 1; > > 2. UPDATE COMPANY SET ADDRESS = '123 Drive' WHERE > COMPANY_ID = 1; > > I want the trigger to ensure that the user must > provide value for NAME when > updating this record. In case 2 above, the updated record will keep the same "name" value that it had previously. The logic that you need to use will depend on precisely what you want to happen. For example, if you expect that the name must change, then you can test "NEW.NAME = OLD.NAME". But if the name is not changing, this will not tell you anything, even if the user is in fact supplying the name. Depending on what rules you want to enforce, you may be better off doing the checking in your application. > > >From: Jeff Eckermann <jeff_eckermann@yahoo.com> > >To: Bernard Cheung <cheungsw@hotmail.com>, > pgsql-sql@postgresql.org > >Subject: Re: [SQL] Trigger function to know which > fields are being updated > >Date: Mon, 10 May 2004 14:38:56 -0700 (PDT) > > > > > >--- Bernard Cheung <cheungsw@hotmail.com> wrote: > > > I am writing a trigger function. How can I know > > > which fields are being > > > updated in the PL/SQL function? > > > > > > For example I have a table here: > > > > > > > > > CREATE TABLE COMPANY ( > > > COMPANY_ID VARCHAR(10) NOT NULL, > > > NAME VARCHAR(30), > > > ADDRESS VARCHAR(30)); > > > > > > I want to write a trigger to block all update > > > statements without updating > > > NAME. I tried the following code block and it > > > doesn't work: > > > > > > > > > IF TG_OP = ''UPDATE'' THEN > > > IF NEW.NAME IS NULL THEN > > > RAISE NOTICE ''Field NAME must be > > > provided!''; > > > END IF; > > > END IF; > > > >That should work. Perhaps "name" is not actually > >null, but rather an empty string? In that case, > your > >test needs to be: "IF NEW.NAME IS NULL OR NEW.NAME > = > >'''' THEN..." > > > > > > > > Are there any functions like the Oracle's > UPDATING() > > > predicate? > > > > > > Bernard Cheung > > > > > > ---------------------------(end of > > > broadcast)--------------------------- > > > TIP 1: subscribe and unsubscribe commands go to > >majordomo@postgresql.org > > _________________________________________________________________ > Linguaphone : Learning English? Get Japanese lessons > for FREE > http://go.msnserver.com/HK/46165.asp > __________________________________ Do you Yahoo!? Win a $20,000 Career Makeover at Yahoo! HotJobs http://hotjobs.sweepstakes.yahoo.com/careermakeover
> --- Bernard Cheung <cheungsw@hotmail.com> wrote: > > Thank you, but my intension is to check whether the user supplies > > NAME when > > updating the record. > > > > For example the trigger shall allow statement 1 and block statement > > 2: > > > > 1. UPDATE COMPANY SET NAME = 'ABC', ADDRESS = '123 Drive' WHERE > > COMPANY_ID = > > 1; > > > > 2. UPDATE COMPANY SET ADDRESS = '123 Drive' WHERE COMPANY_ID = 1; > > > > I want the trigger to ensure that the user must provide value for > > NAME when > > updating this record. > > > > >From: Jeff Eckermann <jeff_eckermann@yahoo.com> > > >To: Bernard Cheung <cheungsw@hotmail.com>, > pgsql-sql@postgresql.org > > >Subject: Re: [SQL] Trigger function to know which fields are being > > updated > > >Date: Mon, 10 May 2004 14:38:56 -0700 (PDT) > > > > > > > > >--- Bernard Cheung <cheungsw@hotmail.com> wrote: > > > > I am writing a trigger function. How can I know > > > > which fields are being > > > > updated in the PL/SQL function? > > > > > > > > For example I have a table here: > > > > > > > > > > > > CREATE TABLE COMPANY ( > > > > COMPANY_ID VARCHAR(10) NOT NULL, > > > > NAME VARCHAR(30), > > > > ADDRESS VARCHAR(30)); > > > > > > > > I want to write a trigger to block all update > > > > statements without updating > > > > NAME. I tried the following code block and it > > > > doesn't work: > > > > > > > > > > > > IF TG_OP = ''UPDATE'' THEN > > > > IF NEW.NAME IS NULL THEN > > > > RAISE NOTICE ''Field NAME must be > > > > provided!''; > > > > END IF; > > > > END IF; > > > > > >That should work. Perhaps "name" is not actually > > >null, but rather an empty string? In that case, your > > >test needs to be: "IF NEW.NAME IS NULL OR NEW.NAME = > > >'''' THEN..." > > > > > > > > > > > Are there any functions like the Oracle's UPDATING() > > > > predicate? > > > > > > > > Bernard Cheung > > > > > > > > ---------------------------(end of > > > > broadcast)--------------------------- > > > > TIP 1: subscribe and unsubscribe commands go to > > >majordomo@postgresql.org > > > > _________________________________________________________________ > > Linguaphone : Learning English? Get Japanese lessons for FREE > > http://go.msnserver.com/HK/46165.asp > > > > > > ---------------------------(end of > > broadcast)--------------------------- > > TIP 5: Have you checked our extensive FAQ? > > > > http://www.postgresql.org/docs/faqs/FAQ.html > One way that comes to my mind is to check if is there any differencebetween the new.name and old.name...something like:if(old.name <> new.name) then -- something happening here...else -- nothing happened, or the name has not been changed.endif;regards, ===== Riccardo G. Facchini