php操作MYSQL数据库无法更新问题解决

function update($table_name, $field, $subquery){$query = '';foreach ($field as $index => $value){ $value = addslashes($value);if (!$query) {$query = "`$index` = '$value'"; }else{$query .= ", `$index` = '$value'";}}$query = "UPDATE `$table_name` SET " . $query . ' ' . $subquery;$link = mysql_query($query);return $link;}用这个函数是下$arr['idata']=$_post['aa']update(data1);