pl/pgsql loop thru columns names - Mailing list pgsql-general

From Dilyan Berkovski
Subject pl/pgsql loop thru columns names
Date
Msg-id 89890.56271.qm@web33105.mail.mud.yahoo.com
Whole thread Raw
Responses Re: pl/pgsql loop thru columns names  (Pavel Stehule <pavel.stehule@gmail.com>)
Re: pl/pgsql loop thru columns names  (Scott Bailey <artacus@comcast.net>)
List pgsql-general
Hi All,

I have a nasty table with many repeating columns of the kind port_ts_{i}_<something>, where {i} is from 0 to 31, and
<something>could be 3 different words. 
I have made a pl/pgsql function that checks those columns from port_ts_1_status to port_ts_31_status and counts
something,however this is nasty and ugly thing to do - repeat 31 times one statement for looping thru {i} and do it 3
timesto loop thru <something>. This is how I do it now: 
REATE OR REPLACE FUNCTION auto_util()
  RETURNS "trigger" AS
$BODY$DECLARE
count_free      integer;
util            real;
BEGIN
count_free = 0;
IF new.port_ts_1_status='free' THEN count_free = count_free + 1;
End if;
IF new.port_ts_2_status='free' THEN count_free = count_free + 1;
End if;
IF new.port_ts_3_status='free' THEN count_free = count_free + 1;
End if;
IF new.port_ts_4_status='free' THEN count_free = count_free + 1;
End if;
IF new.port_ts_5_status='free' THEN count_free = count_free + 1;
End if;
IF new.port_ts_6_status='free' THEN count_free = count_free + 1;
End if;
IF new.port_ts_7_status='free' THEN count_free = count_free + 1;
End if;
.... and till the end ilke this.

Can I do a loop, and make the column naming to be build dynamically (as the dynamic queries in pl/pgsql)?
something like
for i in 1..31 do
Loop
If new.port_ts_[i]_status='free' ... and so on
end Loop.
I tryed but unsuccessfully :(, and can not find much in the documentation.
I am using 8.1 and 8.2 Postgresql DBs.
Someone with an idea?
Thanks




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