HTML Form Select default value from PHP Echo _Post - php

Question

I have a html form where people select to filter the mysql results, example
<select name="display">
<option value="9999" selected>Display all results</option>
<option value="10">10 results only</option>
<option value="20">20 results only</option>
<option value="50">50 results only</option>
<option value="100">100 results only</option>
</select>
But if people select lets say 50 results per page, after form submit I want the option 50 results only to get marked as selected like this
<option value="50" selected>50 results only</option>
The question is How to do this using PHP POST or GET from the form

Answer 1

As I said in comments, assign a variable to a POST array and set it in your LIMIT in the query.
// you can also use isset instead of empty here and GET instead of POST
if(!empty($_POST['display'])) {
$limit = (int)$_POST['display']; // ensure the value is an integer
}
Then place the $limit variable in your query for LIMIT.
I.e.: (and as basic MySQL)
SELECT col1, col2, col3 FROM TABLE WHERE col_x = 'xxx' LIMIT $limit
The question though is a bit unclear so there isn't much else I can add to this.
Sidenote: LIMIT (with SELECT) accepts additional parameters. I.e.: LIMIT 0, 50
[LIMIT {[offset,] row_count | row_count OFFSET offset}]
http://dev.mysql.com/doc/refman/5.7/en/select.html
Edit:
"after form submit I want the option 50 results only to get marked as selected"
In order to keep the value selected, use a conditional statement in the select's options and check if it equals to something:
Sidenote: This will only work if your entire code is inside the same file.
<?php
if(!empty($_POST['display'])) {
$limit = $_POST['display'];
$selected = 'selected';
}
?>
<form action="" method="post">
<select name="display">
<option value="9999" <?php if(isset($selected) && $limit==9999 ) {echo $selected; } ?>>Display all results</option>
<option value="10" <?php if(isset($selected) && $limit==10) {echo $selected; } ?>>10 results only</option>
<option value="20" <?php if(isset($selected) && $limit==20){echo $selected; } ?>>20 results only</option>
<option value="50" <?php if(isset($selected) && $limit==50){echo $selected; } ?>>50 results only</option>
<option value="100" <?php if(isset($selected) && $limit==100){echo $selected; } ?>>100 results only</option>
</select>
<input type="submit" value="submit">
</form>
You can add in the rest of your code.