User-defined function

[phirux]

Hi Larry!

I'm trying to print all sub-category items using my own defined PHP function. There is some thing wrong with this function. Could you please help me to find out the reason why this function doesn’t work. Thanks a lot in advance.

 

<?php
include ('connect.php');
include ('head.html');

echo '<div class="categ"><p class="b">Health</p>';
function retrieve_column($parent){
    $sql = "SELECT item FROM category WHERE parent = $parent ORDER BY item ASC";
    $r = mysqli_query($dbc, $sql);
        if (!$r) {
            echo "Couldn’t make a connection to DB.";
        } else {
            while($row = mysqli_fetch_assoc($r)){
                for ($i=0; $i < mysqli_num_rows($r); $i++) {
                    echo '<a class="text" href="">' . $row['item'][$i] . '</a><br />';
                }
            }
        }
    }

$par = 1;
retrieve_column($par);
mysqli_free_r($r);
mysqli_close($dbc);
?>

 

[Larry]

In what way is it not working? Like what isn't it doing that it should be doing or what is it doing that it shouldn't be? What is the output? What debugging steps have you taken and what were the results?

[phirux]

Hi Larry.

There is no any problem to get connection to database. I used mysqli_error($dbc) and print_r($dbc) to find out if there’s any error, but didn’t get any message. I expect that this function retrieve from database all items which parent value is $parent and show tehm all as a list. If I use a simple code to get connection to database for printing all these items of fields which has same parent value, it will succeed:

$sql = "SELECT 'suo_kat' FROM 'kategoria' WHERE 'parent' = '$parent' ORDER BY 'suo_kat' ASC";
$r = mysqli_query($dbc, $sql);
	if (!$r) {
		echo "Sorry. Try again later." . mysqli_error($dbc);
	} else {
		while($row = mysqli_fetch_assoc($r)){
			echo '<a class="teksti" href="">' . $row['suo_kat'][$i] . '</a><br />';
}

but I’ve to repeat so many times same code in same page to get accomplished the aim.

[Larry]

Ah, okay, that helps! Your function doesn't have access to the database connection so it can't execute the query. I would have thought it'd kick on the !$r error, though. But try passing $dbc to the function as an additional argument and see if it behaves better. 

[phirux]

Thanks for your attention Larry. I've done following changes to my code to confirm that function has access to database. But nothing happened!

function hae_sarake($dbc,$parent){
include ('mysqli_connect_0.php');
$sql = "SELECT 'suo_kat' FROM 'kategoria' WHERE 'parent' = '$parent' ORDER BY 'suo_kat' ASC";
$r = mysqli_query($dbc, $sql);
if (!$r) {
echo "Try again later!" . mysqli_error($dbc);
} else {
while($row = mysqli_fetch_assoc($r)){
for ($i=0; $i < mysqli_num_rows($r); $i++) {
echo '<a class="teksti" href="">' . $row['suo_kat'][$i] . '</a><br />';
}
}
}
}

 

Edited April 22, 2020 by phirux

[phirux]

38 minutes ago, phirux said:

Thanks for your attention Larry. I've done following changes to my code to confirm that function has access to database. But nothing happened!

function hae_sarake($dbc,$parent){
include ('mysqli_connect_0.php');
$sql = "SELECT 'suo_kat' FROM 'kategoria' WHERE 'parent' = '$parent' ORDER BY 'suo_kat' ASC";
$r = mysqli_query($dbc, $sql);
if (!$r) {
echo "Try again later!" . mysqli_error($dbc);
} else {
while($row = mysqli_fetch_assoc($r)){
for ($i=0; $i < mysqli_num_rows($r); $i++) {
echo '<a class="teksti" href="">' . $row['suo_kat'][$i] . '</a><br />';
}
}
}
}

 

The error message i've got as following:

You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for
the right syntax to use near ''kategoria' WHERE 'parent' = '1' ORDER BY 'suo_kat' ASC' at line 1

 

[Larry]

You should print out the query (the $sql) variable to see what the full query is. Sounds like you have a syntax error. 

[phirux]

I've got the following error message:

Unknown column '$parent' in 'where clause'mysqli Object ( [affected_rows] => -1 [client_info] => mysqlnd 5.0.10 - 20111026 - $Id: c85105d7c6f7d70d609bb4c000257868a40840ab $ [client_version] => 50010 [connect_errno] => 0 [connect_error] => [errno] => 1054 [error] => Unknown column '$parent' in 'where clause' [error_list] => Array ( [0] => Array ( [errno] => 1054 [sqlstate] => 42S22 [error] => Unknown column '$parent' in 'where clause' ) ) [field_count] => 0 [host_info] => Localhost via UNIX socket [info] => [insert_id] => 0 [server_info] => 5.5.5-10.2.31-MariaDB [server_version] => 50505 [stat] => Uptime: 776155 Threads: 64 Questions: 118837232 Slow queries: 10 Opens: 910461 Flush tables: 1 Open tables: 2000 Queries per second avg: 153.110 [sqlstate] => 00000 [protocol_version] => 10 [thread_id] => 3055259 [warning_count] => 0 ) 

 

[Larry]

Hmmm...so that's a different error than you had before and doesn't exactly make sense given the code above. What steps had you taken when you got this error?

[phirux]

I've done following changes to code and it's now working correctly:

function hae_sarake($parent, $dbc){
  $sql = "SELECT `suo_kat` FROM `kategoria` WHERE `parent` = '$parent' ORDER BY `suo_kat` ASC";

Thanks for your time.

Edited April 25, 2020 by phirux

[Larry]

Thanks for letting us know!