Echo inside and Echo - php

Question

I'm using echo to sum up the results form a Table. Inside this echo, I place another echo to show all the results form another table. On this page I have an array, I want every item in that array, that is also in the result from the table, to be checked. I use the code below (remember: this code is inside another echo!), it's not functioning, why not?
<?php
$query = "SELECT * FROM profilestemp";
$result = mysql_query($query) or die(mysql_error());
while($row = mysql_fetch_array($result)){
$merkenarray = unserialize($row[merken]);
echo "
A VERY BIG OTHER PART OF THE FORM....
<tr>
<td style=\width:150px;background-color:#a8c11f;padding:2px;\"><p style=\"color:White;font-weight:bold\"><b>Merken</b></p></td>
<td><div id=\"rubrieken\">
<?php
$sql = \"SELECT merknaam FROM merken\";
$result = mysql_query($sql);
while ($row2 = mysql_fetch_array($result)) {
if (isset($merkenarray) && is_array($merkenarray) && in_array($row2[merknaam], $merkenarray)) {
$checked = \"checked='checked'\";
}
else $checked = \"\";
echo \" <input \".$checked.\" type=\"checkbox\" name=\"merken[]\" value='\" . $row2[merknaam] . \"'> \" . $row2[merknaam] . \" <Br /> \";
}
?>
</div></td>
</tr>
}
?>

Answer 1

Instead of using echo in your function, have it return the string to be output. An example:
function functionName() {
return 'Some content to be output';
}
echo functionName();
Additionally, this will give your function more flexibility, as you might not want to echo the result every time, e.g:
function functionName() {
return 'Some content to be output';
}
// Write the result of functionName to a file
file_put_contents('content.txt', functionName());

Answer 2

Your code should look like this
<?php
$query = "SELECT * FROM profilestemp";
$result = mysql_query($query) or die(mysql_error());
while($row = mysql_fetch_array($result)){
$merkenarray = unserialize($row[merken]);
?>
A VERY BIG OTHER PART OF THE FORM....
<tr>
<td style="width:150px;background-color:#a8c11f;padding:2px;"><p style="color:White;font-weight:bold"><b>Merken</b></p></td>
<td><div id="rubrieken">
<?php
$sql = "SELECT merknaam FROM merken";
$result = mysql_query($sql);
while ($row2 = mysql_fetch_array($result)) {
if (isset($merkenarray) && is_array($merkenarray) && in_array($row2[merknaam], $merkenarray)) {
$checked = "checked='checked'";
}
else $checked = "";
echo " <input ".$checked." type="checkbox" name="merken[]" value='" . $row2[merknaam] . "'> " . $row2[merknaam] . " <Br /> ";
}
?>
</div></td>
</tr>
<?php }?>