Thread
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PL/PGSQL help for getting number of rows matched.
Rajesh Kumar Mallah <mallah@trade-india.com> — 2003-11-10T10:49:00Z
Hi, We need to implement following logic efficiently. SELECT * from some_table where .... [ Query 1 ] IF rows_matched = 1 THEN use the single row that matched. ELSIF loop thru the results of [Query 1] END IF; Currently i am doing select count(*) for getting rows_matched in the top and repeating the same query in both branches of IF to get the data of matching rows. I have tried GET DIAGNOSTICS ROW_COUNT but for "SELECTS" if returns 0 or 1 based on matching I am sure there exists better methods. Kindly post a link to better documentation of pl/pgsql or point out section in the standard docs that discuss this issue. Regds Mallah.
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Re: PL/PGSQL help for getting number of rows matched.
Pavel Stehule <stehule@kix.fsv.cvut.cz> — 2003-11-10T12:08:16Z
Hello, it isn't problem. You can write SELECT INTO .... IF FOUND THEN ... END IF or SELECT INTO .. GET DIAGNOSTICS variable = ROW_COUNT; IF variable > 0 THEN ... END IF You can see on http://developer.postgresql.org/docs/postgres/plpgsql-statements.html#PLPGSQL-SELECT-INTO Regards Pavel On Mon, 10 Nov 2003, Rajesh Kumar Mallah wrote: > > Hi, > > We need to implement following logic efficiently. > > SELECT * from some_table where .... [ Query 1 ] > > IF rows_matched = 1 THEN > > use the single row that matched. > > ELSIF > > loop thru the results of [Query 1] > > END IF; > > > Currently i am doing select count(*) for getting rows_matched > in the top and repeating the same query in both branches of IF > to get the data of matching rows. > > I have tried GET DIAGNOSTICS ROW_COUNT but for > "SELECTS" if returns 0 or 1 based on matching > > I am sure there exists better methods. Kindly post a link > to better documentation of pl/pgsql or point out section in > the standard docs that discuss this issue. > > Regds > Mallah. > > > > > ---------------------------(end of broadcast)--------------------------- > TIP 7: don't forget to increase your free space map settings >
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Re: PL/PGSQL help for getting number of rows matched.
Nigel J. Andrews <nandrews@investsystems.co.uk> — 2003-11-10T12:35:19Z
On Mon, 10 Nov 2003, Pavel Stehule wrote: > Hello, > > it isn't problem. You can write > > SELECT INTO .... > IF FOUND THEN > ... > END IF > > or > > SELECT INTO .. > GET DIAGNOSTICS variable = ROW_COUNT; > IF variable > 0 THEN > ... > END IF > > You can see on > http://developer.postgresql.org/docs/postgres/plpgsql-statements.html#PLPGSQL-SELECT-INTO Probably sectino 37.7.4 of the docs ( in http://developer.postgresql.org/docs/postgres/plpgsql-control-structures.html ) is a better source as shown lower. > > On Mon, 10 Nov 2003, Rajesh Kumar Mallah wrote: > > > > > Hi, > > > > We need to implement following logic efficiently. > > > > SELECT * from some_table where .... [ Query 1 ] > > > > IF rows_matched = 1 THEN > > > > use the single row that matched. > > > > ELSIF > > > > loop thru the results of [Query 1] > > > > END IF; > > > > > > Currently i am doing select count(*) for getting rows_matched > > in the top and repeating the same query in both branches of IF > > to get the data of matching rows. > > > > I have tried GET DIAGNOSTICS ROW_COUNT but for > > "SELECTS" if returns 0 or 1 based on matching > > > > I am sure there exists better methods. Kindly post a link > > to better documentation of pl/pgsql or point out section in > > the standard docs that discuss this issue. DECLARE tup RECORD; BEGIN FOR tup IN select * from mytable LOOP Do the required action END LOOP; END Indeed, I'm not even sure how to loop through the results of the query using the scheme you show above. What do you assign the results of the select to? -- Nigel Andrews
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Re: PL/PGSQL help for getting number of rows matched.
Rajesh Kumar Mallah <mallah@trade-india.com> — 2003-11-10T13:48:27Z
On Monday 10 Nov 2003 5:38 pm, Pavel Stehule wrote: > Hello, > > it isn't problem. You can write > > SELECT INTO .... > IF FOUND THEN > ... > END IF I have *different* logic for match=1 and for match > 1 , so FOUND is not a solution as manual says. There is a special variable named FOUND of type boolean. FOUND starts out false within each PL/pgSQL function. It is set by each of the following types of statements: Section 19.5.5 http://www.postgresql.org/docs/7.3/static/plpgsql-statements.html > > or > > SELECT INTO .. > GET DIAGNOSTICS variable = ROW_COUNT; > IF variable > 0 THEN > ... > END IF Even this does not solve my problem. See my actual code and the output. -- ***************** CODE ******************* CREATE OR REPLACE FUNCTION general.copy_accounts() returns integer AS ' DECLARE users_c CURSOR FOR SELECT userid FROM general.user_accounts where userid=46 ; userid_v int; i int; matched int; rec RECORD; BEGIN OPEN users_c; i := 1; LOOP FETCH users_c INTO userid_v; EXIT WHEN NOT FOUND ; SELECT INTO rec profile_id from general.profile_master where userid=userid_v; GET DIAGNOSTICS matched = ROW_COUNT; RAISE INFO ''matched = % '' , matched; SELECT INTO matched count(*) from general.profile_master where userid=userid_v; RAISE INFO ''matched = % '' , matched; EXIT; END LOOP; CLOSE users_c; RETURN 1; END ' LANGUAGE 'plpgsql'; -- ------ CODE ENDS RESULTS BELOW: tradein_clients=# SELECT copy_accounts(); INFO: matched = 1 INFO: matched = 3 Note that matched was 3 but in first place it did not come. +---------------+ | copy_accounts | +---------------+ | 1 | +---------------+ (1 row) Time: 386.76 ms tradein_clients=# Regds Mallah. > > You can see on > http://developer.postgresql.org/docs/postgres/plpgsql-statements.html#PLPGS >QL-SELECT-INTO > > Regards > Pavel > > On Mon, 10 Nov 2003, Rajesh Kumar Mallah wrote: > > Hi, > > > > We need to implement following logic efficiently. > > > > SELECT * from some_table where .... [ Query 1 ] > > > > IF rows_matched = 1 THEN > > > > use the single row that matched. > > > > ELSIF > > > > loop thru the results of [Query 1] > > > > END IF; > > > > > > Currently i am doing select count(*) for getting rows_matched > > in the top and repeating the same query in both branches of IF > > to get the data of matching rows. > > > > I have tried GET DIAGNOSTICS ROW_COUNT but for > > "SELECTS" if returns 0 or 1 based on matching > > > > I am sure there exists better methods. Kindly post a link > > to better documentation of pl/pgsql or point out section in > > the standard docs that discuss this issue. > > > > Regds > > Mallah. > > > > > > > > > > ---------------------------(end of broadcast)--------------------------- > > TIP 7: don't forget to increase your free space map settings -
Re: PL/PGSQL help for getting number of rows matched.
Rajesh Kumar Mallah <mallah@trade-india.com> — 2003-11-10T13:59:36Z
On Monday 10 Nov 2003 6:05 pm, Nigel J. Andrews wrote: > DECLARE > tup RECORD; > BEGIN > FOR tup IN select * from mytable > LOOP > Do the required action > END LOOP; > END > > Indeed, I'm not even sure how to loop through the results of the query > using the scheme you show above. What do you assign the results of the > select to? My working code which i think can be improved is below note that i treat match=1 and match>1 differently. I hope it will answer both of your question. Thanks everyone for the responses though :) Pl/Pgsql itself seems to be the most mature of all PL hence we have decided to shift our business logic from perl layer to DataBase for obvious gains. -- Actual Code------- CREATE OR REPLACE FUNCTION general.copy_accounts() returns integer AS ' DECLARE users_c CURSOR FOR SELECT userid FROM general.user_accounts ; userid_v int; i int; matched int; rec RECORD; BEGIN OPEN users_c; i := 1; LOOP FETCH users_c INTO userid_v; EXIT WHEN NOT FOUND ; SELECT INTO matched count(*) from general.profile_master where userid=userid_v; IF matched = 1 THEN SELECT INTO rec email,title1 , fname1 , mname1 , lname1 , desg1 , mobile from general.profile_master where userid=userid_v; ELSIF matched > 1 THEN -- multiple profiles then get the profile that -- has highest score. SELECT INTO rec email,title1 , fname1 , mname1 , lname1 , desg1 , mobile,source from general.profile_master join general.temp_source_priority using(source) where userid=userid_v order by profile_score(email,title1 , fname1 , mname1 , lname1 , desg1 , mobile) desc limit 1; END IF; IF matched >= 1 THEN i := i + 1; UPDATE general.user_accounts set email= rec.email, title= rec.title1 , fname= rec.fname1 , mname= rec.mname1 , lname= rec.lname1 , desg = rec.desg1 , mobile= rec.mobile where userid = userid_v; END IF; IF i % 100 = 0 THEN RAISE INFO '' copied % accounts '' , i; END IF; END LOOP; CLOSE users_c; RAISE INFO '' Successfully finished with % accounts '' , i; RETURN 1; END ' LANGUAGE 'plpgsql';