MySQL not decrementing values - php

Question

I can't get the values in the table Accounts to decrement when I try to delete a post. The values I would like to decrement are "PostCount", "Likes Count" and "CommentsCount". Currently only the "PostCount" works.
Please can you tell me what I am doing wrong:
$arg = mysql_query("SELECT `numberOfLikes` FROM Posts WHERE `id` = '$postID'") or die(mysql_error());
$query = mysql_query("SELECT * FROM Likes WHERE `postID` = '$postID'");
while ($row = mysql_fetch_assoc($query)) {
$b = $row['accountID'];
mysql_query("UPDATE Accounts SET `numberOfLikes` = (`numberOfLikes` - 1) WHERE `id` = '$b'");
}
$arg = mysql_query("SELECT `numberOfComments` FROM Posts WHERE `id` = '$postID'");
$query = mysql_query("SELECT * FROM Posts WHERE `id` = '$postID'");
while($row = mysql_fetch_assoc($arg)) {
$b = $row['accountID'];
mysql_query("UPDATE Accounts SET `CommentsCount` = (`CommentsCount` - 1) WHERE `id` = '$b'");
}
$arg = mysql_query("SELECT `PostCount` FROM Accounts WHERE `id` = '$accountID'");
while ($row = mysql_fetch_assoc($arg)) {
mysql_query("UPDATE Accounts SET `PostCount` = (`PostCount` - 1) WHERE `id` = '$accountID'");
}
mysql_query("DELETE FROM Likes WHERE `postID` = '$postID'");
mysql_query("DELETE FROM Comments WHERE `postID` = '$postID'");
mysql_query("DELETE FROM Posts WHERE `id` = '$postID' AND `accountID` = '$accountID'") or die(mysql_error());
exit("Deleted post");

Answer 1

First up looping queries kills your execution time. You want to limit it to as little queries as possible, this is where implode comes into play:
// what is this for? I do not see it being used. $arg = mysql_query("SELECT `numberOfLikes` FROM Posts WHERE `id` = '$postID'") or die(mysql_error());
$query = mysql_query("SELECT * FROM Likes WHERE `postID` = '$postID'");
while ($row = mysql_fetch_assoc($query)) {
$b[] = $row['accountID'];
}
mysql_query("UPDATE Accounts SET `numberOfLikes` = (`numberOfLikes` - 1) WHERE `id` IN(" . implode(',', $b) . ")") or trigger_error('MySQL Update Failed: ' . mysql_error());
This will be much more efficient and have to same effect.
The next query, should be similar:
$arg = mysql_query("SELECT `numberOfComments` FROM Posts WHERE `id` = '$postID'");
// again an extra unnecessary query not being used. $query = mysql_query("SELECT * FROM Posts WHERE `id` = '$postID'");
$b=array();
while($row = mysql_fetch_assoc($arg)) {
$b[] = $row['accountID'];
}
mysql_query("UPDATE Accounts SET `CommentsCount` = (`CommentsCount` - 1) WHERE `id` IN(".implode(',', $b) . ")") or trigger_error(mysql_error());
This next one, I do not even know why you are looping through it:
//$arg = mysql_query("SELECT `PostCount` FROM Accounts WHERE `id` = '$accountID'");
//while ($row = mysql_fetch_assoc($arg)) {
mysql_query("UPDATE Accounts SET `PostCount` = (`PostCount` - 1) WHERE `id` = '$accountID'") or trigger_error(mysql_error());
//}
As you are not utilizing that data anywhere, just run the update query.
Implementing the above should speed up your application and reduce redundancy. implode is very handy and running 1 query vs several is almost always preferred. I am not sure if that will solve your problem, but it is a huge step in the right direction in fixing your code.

Answer 2

I re-coded my if statement containing the code I posted and it is now working perfectly:
mysql_query("UPDATE Accounts SET `PostCount` = (`PostCount` - 1) WHERE `id` = '$accountID'");
$query = mysql_query("SELECT * FROM Likes WHERE `postID` = '$postID'") or die(mysql_error());
while($row = mysql_fetch_assoc($query)) {
$accID = $row['accountID'];
mysql_query("UPDATE Accounts SET `Likes Count` = (`Likes Count` - 1) WHERE `id` = '$accID'");
}
$query = mysql_query("SELECT * FROM Comments WHERE `postID` = '$postID'");
while($row = mysql_fetch_assoc($query)) {
$accID = $row['accountID'];
mysql_query("UPDATE Accounts SET `CommentsCount` = (`CommentsCount` - 1) WHERE `id` = '$accID'");
}
mysql_query("DELETE FROM Likes WHERE `postID` = '$postID'");
mysql_query("DELETE FROM Comments WHERE `postID` = '$postID'");
mysql_query("DELETE FROM Posts WHERE `id` = '$postID' AND `accountID` = '$accountID'") or die(mysql_error());
exit("Deleted post");