[RESOLVED] double while loops to populate select box

[ffsja]

I'm trying to fill a select box in the update form so that multiple values in the select box are highlighted if the user previously selected multiple values, one if they only selected one value, and zero if they didn't select any values. The main problem I'm having writing this code is that I need to draw the values for the select box from two tables: the sections table which populates the entire possible range of select box values and the sections_x table which includes only the values that have been selected.

What I've come up with so far is a double while loop:

while ($row = mysql_fetch_array($result5)) {
$section_id = $row['section_id'];
$section = $row['section'];
while ($row = mysql_fetch_array($result8)) {
$section_id_x = $row['section_id'];
$date_id_x = $row['date_id'];
if ($section_id == $section_id_x) {
$option_block5 .= "<option value=\"$section_id\" selected=\"selected\">$section</option>";
} else {
$option_block5 .= "<option value=\"$section_id\">$section</option>";
}
}
}

However, the select box is just showing up blank.

Any suggestions?

Thanks,
S./

[Roger_Ramjet]

Best done with a LEFT JOIN in your query: sections LEFT JOIN section_x
This will return all from the sections table, and either the selected values from the section_x table or NULL, You don't show your queries so I can't tell if/how the query could be written.

The you test for NULL in the single while loop and add 'selected' if not null.

You could also do it with arrays if the joined query is absolutely not possible; but the sql option is the best.

[ffsja]

That seems to work, except that if the value was selected I can't unselect it and save it as unselected - it keeps showing up as selected regardless.

Here's the join sql:

$sql5 = "SELECT * FROM $table_name8 LEFT JOIN $table_name2 using (section_id)";

$result5 = @($sql5,$connection) or die(mysql_error());

And here's the while statement i made to populate the select box:

while ($row = mysql_fetch_array($result5)) {
$section_id = $row['section_id'];
$date_id = $row['date_id'];
$section = $row['section'];

if ($section_id == NULL) {
	$option_block5 .= "<option value=\"$section_id\" selected=\"selected\">$section</option>";
} else {
	$option_block5 .= "<option value=\"$section_id\">$section</option>";
}

}

What do you think?

Thanks,
S./

[ffsja]

Never mind - I just switched it to != NULL and it works fine.

Thanks for you help!!

S./