$sql = 'ALTER TABLE `$dbprefixuser` ADD `test` CHAR(1) CHARACTER SET latin1 COLLATE latin1_bin NOT NULL;';
$sql = 'ALTER TABLE `'. $dbprefix . 'user` ADD `test` CHAR(1)...';
$query="SELECT * FROM `'. $dbprefix . 'user` WHERE user_name='$search';";
$query='SELECT * FROM `'. $dbprefix . 'user` WHERE user_name='$search';';