Record numbering

inexion

Why is it that when a set of records are imported with a primary key row 'id' thats auto incremented, the $i value through a foreach statement never returns the zeroth record??

I guess an example would be like...

$i = 0;
foreach($array as $key => $value){
$value = $i;

echo "$records['id'][$i]<br />";

}
echo sizeof($records['id'];

If I have 10,001 records......this sizeof function should return 10,000 (which is fine).
Inside the database in theory, the record with 'id' = 1 is actually the zeroth record, but why would that matter....why is the zeroth record skipped during output here?

Thanks!

laserlight

If I have 10,001 records......this sizeof function should return 10,000 (which is fine).

If you have 10001 records and placed them into $array, and sizeof($array) returns 10000, then clearly one record is missing from $array. Since "the zeroth record skipped during output", we can conclude that that is the missing record. The bug probably lies in the code that populates $array.

inexion

i thought that when you sizeof or count an array with 10,001 rows/records in mySQL the array's size/count would be 10,000 because of the zeroth element(?)

laserlight

i thought that when you sizeof or count an array with 10,001 rows/records in mySQL the array's size/count would be 10,000 because of the zeroth element(?)

Write a simple script to prove that you are correct, and you will find your answer in the process. Note that this has nothing to do with MySQL, and everything to do with PHP arrays and the PHP [man]count/man and sizeof() functions.

laserlight

i thought that when you sizeof or count an array with 10,001 rows/records in mySQL the array's size/count would be 10,000 because of the zeroth element(?)

NogDog

count()/sizeof() returns the number of elements in the array. It does not care what the index of the last element is (or of any other element), it simply counts the total number of elements. A count() of the following arrays would return 3 in all three cases:

$arr1 = array('zero', 'one', 'two');
$arr2 = array(2 => 'two', 4 => 'four', 6 => 'six');
$arr3 = array('tom' => 'jones', 'frank' => 'sinatra', 'bing' => 'crosby');

inexion

there has got to be a bug with how i'm populating my arrays...

$query_targets = "Select * from table";
$rs_targets = mysql_query($query_targets, $conn) or die('Error connecting, query failed'.mysql_error());
$row_targets = mysql_fetch_array($rs_targets) or die ('Error connecting, query failed'.mysql_error());

$targets = array
(
"id"=>array(),
"name"=>array()
);

while($row_targets = mysql_fetch_array($rs_targets))
{
	$chid = $row_targets['nid'];
	$targets['id'][] = $chid;
	$named = $row_targets['name'];
	$targets['name'][] = $named;
}

inexion

ok so after some testing i'm still really confused...

here are some results:

$i=0;
while($row_targets = mysql_fetch_array($rs_targets))
{
	$chid = $row_targets['nid'];
	$targets['id'][] = $chid;
	echo "bah humbug $i {$targets['id'][$i]} <br />"; 
$i++;
}

returns:
bah humbug 0 1287-0308954
bah humbug 1 1287-0308955
bah humbug 2 1287-0308957
bah humbug 3 1287-0308958
bah humbug 4 1287-0308959
bah humbug 5 1287-0308960

(missing first record!)

$i=0;
while($i < mysql_num_rows($rs_targets)){

$chid = $row_targets['nid'];
$targets['id'][] = $chid;

$i++;
}

foreach($targets['id'] as $key => $value){
echo "bah humbug $key $value <br />";
}

returns:

bah humbug 0 1287-0308952
bah humbug 1 1287-0308952
bah humbug 2 1287-0308952
bah humbug 3 1287-0308952
bah humbug 4 1287-0308952
bah humbug 5 1287-0308952

at least its getting the number of records right ($i).....and that $value it keeps repeating is actually the first record in the mysql table.....so in order the records should be:

bah humbug 0 1287-0308952
bah humbug 1 1287-0308954
bah humbug 2 1287-0308955
bah humbug 3 1287-0308957
bah humbug 4 1287-0308958
bah humbug 5 1287-0308959

#3 (original code)

while($row_targets = mysql_fetch_array($rs_targets))
{
	$chid = $row_targets['nid'];
	$targets['id'][] = $chid;

}

foreach($targets['id'] as $key => $value){
echo "bah humbug $key $value <br />";
}

returns:

bah humbug 0 1287-0308954
bah humbug 1 1287-0308955
bah humbug 2 1287-0308957
bah humbug 3 1287-0308958
bah humbug 4 1287-0308959
bah humbug 5 1287-0308960

(still missing first record)

any ideas much appreciated, this is fun =D

NogDog

Do you by any chance have a spurious mysql_fetch_*() call of some sort before you start the loop? If so, get rid of it if it's not needed, as it would be incrementing the result row pointer. Or if you need it for some reason, then you'll need to use mysql_data_seek() to reset it back to 0.

inexion

I neglected to mention that before each of the examples I just displayed here, is the following beginning code:

$query_targets = "Select * from targets";
$rs_targets = mysql_query($query_targets, $conn) or die('Error connecting, query failed'.mysql_error());
$row_targets = mysql_fetch_array($rs_targets) or die('Error connecting, query failed'.mysql_error());

$targets = array
(
"id"=>array(),
"name"=>array()
);

so how exactly would I repair this then? thanks

laserlight

What is the purpose of this line?

$row_targets = mysql_fetch_array($rs_targets) or die('Error connecting, query failed'.mysql_error());

inexion

as far as I know $row_targets just fills up as an array with the results of the query, no(?)

also, in the examples listed above, when filling the other arrays, it uses $row_targets for column reference

NogDog

mysql_fetch_array() reads one result row and returns it as an array, and moves the result row pointer to the next row. This is why the loop that follows is starting with the 2nd result row. Looks to me like you can just delete that line and be done with it.

inexion

easier said than done, except that each example above uses it with $row_targets, and mysql_data_seek() didn't work unless I put it in the wrong place...

how would you manipulate this code to only use one fetch?

$query_targets = "Select * from targets";
$rs_targets = mysql_query($query_targets, $conn) or die('Error connecting, query failed'.mysql_error());
$row_targets = mysql_fetch_array($rs_targets) or die('Error connecting, query failed'.mysql_error());

$targets = array
(
"id"=>array(),
"name"=>array()
);


while($row_targets = mysql_fetch_array($rs_targets))
{
	$chid = $row_targets['nid'];
	$targets['id'][] = $chid;

}

foreach($targets['id'] as $key => $value){
echo "bah humbug $key $value <br />";
}

NogDog

Just get rid (for now just comment it out) of the line in red below, and I'll bet the problem is solved.

$query_targets = "Select * from targets";
$rs_targets = mysql_query($query_targets, $conn) or die('Error connecting, query failed'.mysql_error());
[color=red]// not needed and is messing up the result row pointer:
$row_targets = mysql_fetch_array($rs_targets) or die('Error connecting, query failed'.mysql_error());[/color]

$targets = array
(
"id"=>array(),
"name"=>array()
);

inexion

whoa, it worked - i'm still confused though.....

i thought that $row_targets was defined by the trouble maker fetch, so how is the rest of the code working without that assignment?

thanks again for the help of course =]

NogDog

It's defined within each iteration of your while loop below that. Each time through the loop the fetch command retrieves one row from the query result set, and then you are adding that row to your $targets array.

The thing to remember is that each call to a mysql_fetch_*() type function only retrieves one row, and each successive call retrieves the next row or else returns false if there are no more rows (which is why your while loop is not an infinite loop).

inexion

hah i've been mistaking that for ==

case closed =)