RE: [PHP-DB] One big query vs. lots of small queries

I would think the one huge query (using an IN clause) would be better than multiple queries...especially if you structure it to use an index $query="UPDATE some_table SET x='$y' WHERE id IN('.$z[$key].','.$z[$another_key].','.$z[$another_key]... bastien

From: Jeffrey <jeffrey@ungodly.com> To: PHP DB <php-db@lists.php.net> Subject: [PHP-DB] One big query vs. lots of small queries Date: Mon, 18 Dec 2006 15:23:36 +0100 Here's a question of efficiency. I have an application in PHP using MySQL. Users select items on a form and each selected item represents a change in a table row. It is possible that 100s of changes might be chosen from a single form. Which is likely to be faster/more efficient? multiple queries like... $query="UPDATE some_table SET x='$y' WHERE id='$z[$key]'"; $result=mysql_query($query); or one huge query like... $query="UPDATE some_table SET x='$y' WHERE id='$z[$key]' OR id='$z[$another_key]' OR id='$z[$another_key] OR id='$z[$another_key]"; etc? $result=mysql_query($query); In the latter, PHP would have to construct the WHERE string, which would require some processing power as well. Is there a limit to how many OR's can be added to a mysql query? No - don't answer that, I'll look in the manual. Many thanks, Jeff -- PHP Database Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php

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