Question

大家好，我有这个数据库架构：

table books [id,title,description,date_released]
-------------------------------------------------------
table authors [id,name]
table books_authors[book_id,author_id]
ALTER TABLE `books_authors`
  ADD CONSTRAINT `books_authors_ibfk_1` FOREIGN KEY (`book_id`) REFERENCES `books` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  ADD CONSTRAINT `books_authors_ibfk_2` FOREIGN KEY (`author_id`) REFERENCES `authors` (`id`) ON DELETE CASCADE ON UPDATE CASCADE;
--------------------------------------------------------
table categories [id,name]
table books_authots[book_id,category_id]
ALTER TABLE `books_categories`
  ADD CONSTRAINT `books_categories_ibfk_1` FOREIGN KEY (`book_id`) REFERENCES `books` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  ADD CONSTRAINT `books_categories_ibfk_2` FOREIGN KEY (`category_id`) REFERENCES `categories` (`id`) ON DELETE CASCADE ON UPDATE CASCADE;
--------------------------------------------------------
table books_locations [id,name]
table books_locations [book_id,location_id]
ALTER TABLE `books_locations`
  ADD CONSTRAINT `books_locations_ibfk_1` FOREIGN KEY (`book_id`) REFERENCES `books` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  ADD CONSTRAINT `books_locations_ibfk_2` FOREIGN KEY (`location_id`) REFERENCES `locations` (`id`) ON DELETE CASCADE ON UPDATE CASCADE;

查询是：

$sql = "SELECT DISTINCT bk.title AS Title, YEAR(bk.date_released) AS Year, bk.price   AS Price, cat.name AS Category, aut.name AS Author FROM books bk

       JOIN books_authors bk_aut
          ON bk_aut.book_id = bk.id

       JOIN authors aut
          ON aut.id = bk_aut.author_id

       JOIN books_categories bk_cat
          ON bk_cat.book_id = bk.id

        JOIN categories cat
          ON cat.id = bk_cat.cat_id  
          
          JOIN books_locations bk_loc
          ON bk_cat.book_id = bk.id

        JOIN locations loc
          ON loc.id = bk_loc.loc_id          
";

if (isset($_GET['srch_for'])){

      $locations = array();
      $getters = array();
      $queries = array();

      foreach($_GET as $key => $value) {
        $temp = is_array($value) ? $value : intval(trim($value));
        if (!empty($temp)) {
          list($key) = explode("-",$key);
          if ($key == 'srch_locations'){
            array_push($locations,$value);
          }
          if (!in_array($key,$getters)){
            $getters[$key] = intval(trim($value));
          }
        }
      }

      if (!empty($locations)) {
        $loc_qry = implode(",",$locations);
      }

      if(!empty($getters)) {

        foreach($getters as $key => $value){
          ${$key} = $value;
          switch($key) {
            case 'srch_for':
            array_push($queries, "(bk.title LIKE '%$srch_for%' || bk.description LIKE '%$srch_for%' || bk.isbn LIKE '%$srch_for%')");
          
            case 'srch_author':
            array_push($queries, "bk_aut.author_id = $srch_author");
            break;
            case 'srch_language':
            array_push($queries, "bk_cat.cat_id = $srch_category");
            break;
            case 'srch_locations':
            array_push($queries, "bk_loc.location_id IN ($loc_qry)");
            break;
            
          }
       }
    }
     
     if(!empty($queries)) {
         $sql .= " WHERE ";
         $i=1;
         foreach($queries as $query) {
             if ($i < count($queries)) {
                 $sql .= $query." AND ";
             }else{
                 $sql .= $query;
             }
             $i++;
         }

     }

      $sql .= " ORDER BY bk.title ASC";
  }

我想按Min（价格）和Max（价格）对书籍进行排序这是正确的查询吗？

$sql = "SELECT DISTINCT (bk.title AS Title, YEAR(bk.date_released) AS Year, bk.price   AS Price, cat.name AS Category, aut.name AS Author), min(price), max(price)  FROM books bk .....";

和我分组的地方？能帮到我吗，谢谢你提前

Answer 1

看起来你需要这样的东西（不需要distinct）：

select 
    bk.title   as Title
  , year(bk.date_released) as Year
  , pr.price   as Price
  , cat.name   as Category
  , aut.name   as Author
  , min(price) as minPrice
  , max(price) as maxPrice
from books bk
  inner join books_categories bkcat
    on bk.book_id = bkcat.book_id
  inner join categories cat
    on bkcat.cat_id = cat.cat_id
  inner join books_authors bkaut
    on bk.book_id = bkaut.book_id
  inner join authors aut
    on bkaut.author_id = aut.author_id
group by 
    bk.title
  , year(bk.date_released) 
  , pr.price
  , cat.name
  , aut.name

如何在此查询中添加最小和最大价格

1 个答案: