php内部查询mysql条件语法

Question

$category = get_option('category');

// checks to see if subcategory is enabled in the option page  
if ( get_option('enable_subcategory') == 'y' ):   

  $subcategory = get_option('subcategory');

endif;

$qry = mysql_query("SELECT car,number FROM ".$table." 
                    WHERE category = '$category' AND subcategory = '$subcategory' 
                    ORDER BY RAND() LIMIT 20");

如何在不启用子类别选项的情况下编写$ query以使“AND subcategory ='$ subcategory'”消失？

Answer 1

添加了$subSql var：

<?

  $category = get_option('category');

  if ( get_option('enable_subcategory') == 'y' ):   // checks to see if subcategory is enabled in the option page  

  $subcategory = get_option('subcategory');
  $subSql = "AND subcategory = '$subcategory'";

  endif;

  $qry = mysql_query("SELECT car,number FROM ".$table." WHERE category = '$category' $subSql ORDER BY RAND() LIMIT 20");

?>