PHP Warning: mysql_fetch_assoc() expects parameter 1 to be resource, boolean given...

I am working on a recently-inherited legacy database.  One of the tables is structured in a way that is unsuitable for its purpose, so I need to take the data and place it in another table that is suitable.

I have created the new table: four TINYINT columns that will be set either as 0 (default) or 1.  A sufficient number of rows exists showing default values.  I intend to update each row by scrolling through the relevant data from the old table.

Unfortunately, I can't loop through the data because I keep getting the warning above (it's the same with mysql_fetch_array).

The query is good: if I cut and paste it into phpMyAdmin I get c.39,000 rows returned, as expected.

The connection is good: it's all handled by the same includes used in the working system.  To check, I have added error-handling from the working pages, and that reports no errors.

The PHP version of the query seems to be good - if I comment out the while() loop and substitute print_r, it tells me that the mysql_query is returning Resource id #5.

But the loop doesn't loop.  It puts values from the first row retrieved into $ue and $hpc; and it does update the correct row in the new table as it should.  But that's it (apart from throwing the Warning above).

	//Retrieve relevant contents of original table
	$sql = mysql_query("SELECT `user_entry_FK`, `hpc_standard_FK` FROM member_standards ORDER BY `user_entry_FK`");
//	print_r ($sql);

	//Amend fields in target table
 	while ( $array  = mysql_fetch_assoc($sql) ) {
 		$ue = $array['user_entry_FK'];
 		$hpc = $array['hpc_standard_FK'];
 		switch ($hpc) {
 			case 1:
 			$sql = mysql_query ("UPDATE user_HPC SET `hpc1` = 1 WHERE `enid_FK` =$ue");
 			case 2:
 			$sql = mysql_query ("UPDATE user_HPC SET `hpc2` = 1 WHERE `enid_FK` =$ue");
 			case 3:
 			$sql = mysql_query ("UPDATE user_HPC SET `hpc3` = 1 WHERE `enid_FK` =$ue");
 			case 4:
 			$sql = mysql_query ("UPDATE user_HPC SET `hpc4` = 1 WHERE `enid_FK` =$ue");

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Where am I going wrong?
Who is Participating?
Beverley PortlockConnect With a Mentor Commented:
Your are storing the resource ID in $sql on line 2 of the fragment above. Inside the loop you then assign $sql a new value based on the UPDATE query thus wiping out your resource ID.

Assign the queries in the loop to some other variable. For UPDATE queries only TRUE or FALSE is returned, not a resource id so on the next loop iteration $sql contain a boolean which throws the error message.
hnmccAuthor Commented:
Well it's obvious - once someone points it out...
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