postgres woes

[Anon]

while working on a psql table I have found, that for some reason when my script causes the following warnings:

Warning: Unable to jump to row 17 on PostgresSQL result index 2 in /usr/local/apache/htdocs/webroot/scripts/banner4.php on line 38

Warning: Unable to jump to row 17 on PostgresSQL result index 2 in /usr/local/apache/htdocs/webroot/scripts/banner4.php on line 39

Warning: Unable to jump to row 17 on PostgresSQL result index 2 in /usr/local/apache/htdocs/webroot/scripts/banner4.php on line 40

Warning: Unable to jump to row 17 on PostgresSQL result index 2 in /usr/local/apache/htdocs/webroot/scripts/banner4.php on line 41

this confuses me simply becuase it only happens on the last row of my table.

require("dbconect.inc.php");

$result = pg_exec($db, "SELECT * FROM comm ORDER BY id DESC;");
$numrows = pg_numrows($result);

srand((double)microtime()*100000);
$ran1 = rand(1,$numrows);
$ran2 = rand(1,$numrows);
while($ran2 == $ran1){
$ran2 = rand(1,$numrows);
}

$ran3 = rand(1,$numrows);
while($ran3 == $ran1 || $ran3 == $ran2){
$ran3 = rand(1,$numrows);
}
$ran4 = rand(1,$numrows);
while($ran4 == $ran1 || $ran4 == $ran2 || $ran4 == $ran3){
$ran4 = rand(1,$numrows);
}

[Anon]

Your rand generator should go from 0 to (numrows-1).

Right?

Tim

[Anon]

normaly I'd say yes but the id values in my table start at 1. I even get the same results when rand(1,$numrows) is changed to rand(0,$numrows)

[Anon]

What exactly are you trying to do here? Where is the code that is generating the errors?

And as I mentioned (numrows-1) is the last row in a result set. The result set starts at 0.

[Anon]

my applogies, I was misinterpreting what you had posted. Things are now working smoothly and I appretiate the help.

[Anon]

the result set start from 0 to (numrows - 1)
just do that

rand (....) - 1;

[Anon]

$numrows is returning the number of rows that are stored in the $result array. But the array begins at 0, not one. Try
rand(0,$numrows-1); in place of rand(1,$numrows);