max(id) and limit 10, but use them in different places - php

Question

I have two tables, posts and sections. I want to get the last 10 posts WHERE section = 1,
but use the 10 results in different places. I make a function:
function sectionposts($section_id){
mysql_set_charset('utf8');
$maxpost1 ="SELECT max(id) from posts WHERE section_id = $section_id ORDER BY ID DESC LIMIT 20";
$maxpost12 =mysql_query($maxpost1);
while ($maxpost_rows = mysql_fetch_array($maxpost12 ,MYSQL_BOTH)){
$maxpost2 = $maxpost_rows[0];
}
$query = "SELECT * FROM posts WHERE id = $maxpost2";
$query2 = mysql_query($query);
return $query2;
}
$query2 = sectionposts(6);
while ($rows = mysql_fetch_array($query2)){
echo $rows['title'] . "<br/>" . "<br/>";
echo $rows['id'] . "<br/>" . "<br/>";
echo $rows['image_section'] . "<br/>";
echo $rows['subject'] . "<br/>";
echo $rows['image_post'] . "<br/>";
}
How can it take these ten results but use them in different places, and keep them arranged from one to ten.
this was the old case and i solve it but i found another problem, that, if the client had deleted a post as id = 800 "so there aren't id = 800 in DB" so when i get the max id minus $NUM from it, and this operation must be equal id = 800, so i have a programing mistake here, how can i take care of something like that.
function getmax_id_with_minus ($minus){
mysql_set_charset('utf8');
$maxid ="SELECT max(id) FROM posts";
$maxid1 =mysql_query($maxid);
while ($maxid_row = mysql_fetch_array($maxid1)){
$maxid_id = $maxid_row['0'];
$maxid_minus = $maxid_id - $minus;
}
$selectedpost1 = "SELECT * FROM posts WHERE id = $maxid_minus";
$query_selectedpost =mysql_query($selectedpost1);
return ($query_selectedpost);
}
<?php
$ss = getmax_id_with_minus (8);
while ($rows = mysql_fetch_assoc($ss)){
$main_post_1 = $rows;
?>
anyway "really" thanks again :) !

Answer 1

A few thoughts regarding posted code:
First and foremost, you should stop using mysql_ functions as they are being deprecated and are vulnerable to SQL injection.
$maxpost1 ="SELECT max(id) from posts WHERE section_id = $section_id ORDER BY ID DESC LIMIT 20";
When you SELECT MAX, MIN, COUNT, AVG ... functions that only return a single row, you do not need an ORDER BY or a LIMIT.
Given that you are only asking for the MAX(id), you can save work by combining your queries like so:
SELECT * FROM posts
WHERE id = (SELECT MAX(id) from posts WHERE section_id = $section_id)
If I'm understanding what you're trying to do (please correct me if I'm wrong), your function would look something like:
function sectionposts($section_id) {
$link = mysqli_connect("localhost", "my_user", "my_password", "world");
$stmt = mysqli_prepare($link, "SELECT title, id, image_section, subject, image_post FROM posts "
. "WHERE section_id = ? ORDER BY id DESC LIMIT 10");
mysqli_stmt_bind_param($stmt, $section_id);
return mysqli_query($link, $stmt)
}
$result = sectionposts(6);
while ($row = mysqli_fetch_assoc($result)) {
echo $rows['title'] . "<br /><br />";
echo $rows['id'] . "<br /><br />";
echo $rows['image_section'] . "<br />";
echo $rows['subject'] . "<br />";
echo $rows['image_post'] . "<br />";
}

Answer 2

Try this instead, to save yourself a lot of pointless code:
$sql = "SELECT * FROM posts WHERE section_id=$section_id HAVING bar=MAX(bar);"
$result = mysql_query($sql) or die(mysql_error());
$row = mysql_fetch_assoc($result);
echo ...;
echo ...;
The having clause lets you find the max record in a single operation, without the inherent raciness of your two-query version. And unless you allow multiple records with the same IDs to pollute your tables, removing the while() loops also makes things far more legible.

Answer 3

Seems like you want to store them in an array.
$posts = array(); //put this before the while loop.
$posts[] = $row; //put this in the while loop