PHP AND子句不显示结果，但OR是

Question

我有一个图书搜索正在搜索我想要搜索的图书，这些图书可以搜索共享作者类别或发布者的图书。我有它设置，它适用于OR条款，例如具有与他们相关的类别CHILDRENS或HISTORY的书籍，这可以正常工作，但是当我搜索属于2类别（AND）的书籍时，例如CHILDRENS AND MAGIC（Harry Potter）它即使它们在数据库中链接，也不显示这些书。

以上是我使用OR进行的搜索，当我搜索属于儿童和历史的书籍时

上面你可以看到，当Harrypotter的书籍属于这两本书时，我得不到分享儿童和魔法书籍的结果。 上面是数据库中的链接，它为每本书分类，Magic是Category 1，Childrens是Category 2，你可以看到他们都分享这些。

以下是查询的PHP代码

<?php
include 'header.php';
include 'searchscriptTEST.php';

$sql =  "SELECT DISTINCT bk.title AS Title, bk.bookid AS BookID, bk.year AS Year, bk.publisher AS Publisher, aut.authorname AS Author 
         FROM book bk 

         JOIN book_category bk_cat 
         ON bk_cat.book_id = bk.bookid

         JOIN categories cat 
         ON cat.id = bk_cat.category_id

         JOIN books_authors bk_aut 
         ON bk_aut.book_id = bk.bookid

         JOIN authors aut
         ON aut.id = bk_aut.author_id";

if(isset($_GET['searchInput'])){
$input = $_GET['searchInput'];
$input = preg_replace('/[^A-Za-z0-9]/', '', $input);
}
if (isset($input)){

    $getters = array();
    $queries = array();

    foreach ($_GET as $key => $value) {
        $temp = is_array($value) ? $value : trim($value);
        if (!empty($temp)){
        if (!in_array($key, $getters)){
            $getters[$key] = $value;
            }
        }
    }

    if (!empty($getters)) {

        foreach($getters as $key => $value){
            //${$key} = $value;
            switch ($key) {
                case 'searchInput':
                    array_push($queries,"(bk.title LIKE '%{$getters['searchInput']}%' 
                    || bk.description LIKE '%{$getters['searchInput']}%' || bk.isbn LIKE '%{$getters['searchInput']}%' 
                    || bk.keywords LIKE '%{$getters['searchInput']}%' || aut.authorname LIKE '%{$getters['searchInput']}%')");
                break;
                case 'srch_publisher':
                    array_push($queries, "(bk.publisher = '{$getters["srch_publisher"]}')");
                break;
                case 'Year':
                    if(isset($getters['Year1']) ==""){
                        array_push($queries, "(bk.year = '{$getters['Year']}')");
                    } else {
                        array_push($queries, "(bk.year BETWEEN '$value' AND '{$getters['Year1']}')");
                    }
                break;
                case 'srch_author':
                     if(isset($getters['authorOperator']) ==""){
                    array_push($queries, "(bk_aut.author_id = '{$getters["srch_author"]}')");
                    } else {
                        $operator = $getters['authorOperator'];
                        array_push($queries, "(bk_aut.author_id = '$value' $operator bk_aut.author_id = '{$getters['srch_author1']}')");
                    }
                break;
                case 'srch_category':
                     if(isset($getters['catOperator']) ==""){
                        array_push($queries, "(bk_cat.category_id = '{$getters["srch_category"]}')");
                    } else {
                        $operator1 = $getters['catOperator'];
                        array_push($queries, "(bk_cat.category_id = '$value' $operator1 bk_cat.category_id = '{$getters['srch_category1']}')");
                    }
                break;

        }
    }
}
if(!empty($queries)){
    $sql .= " WHERE ";
    $i = 1;
    foreach ($queries as $query) {
        if($i < count($queries)){
            $sql .= $query." AND ";
        } else {
            $sql .= $query;
        }   
        $i++;
    }
}
$sql .= " GROUP BY bk.title ORDER BY bk.title ASC";
var_dump($sql);

}else{
    $sql .= " GROUP BY bk.title ORDER BY bk.title ASC";
}


$rs = mysql_query($sql) or die(mysql_error());
$rows = mysql_fetch_assoc($rs);
$tot_rows = mysql_num_rows($rs);
?>

这是发送到数据库的SQL Dump，

SELECT
  DISTINCT bk.title AS Title,
  bk.bookid AS BookID,
  bk.year AS Year,
  bk.publisher AS Publisher,
  aut.authorname AS Author 
FROM book bk
  JOIN book_category bk_cat ON bk_cat.book_id = bk.bookid
  JOIN categories cat ON cat.id = bk_cat.category_id
  JOIN books_authors bk_aut ON bk_aut.book_id = bk.bookid
  JOIN authors aut ON aut.id = bk_aut.author_id 
WHERE
  (bk_cat.category_id = '2' AND bk_cat.category_id = '1')
GROUP BY bk.title
ORDER BY bk.title ASC

Answer 1

格式化查询以使其实际可读后，您会看到以下行：

bk_cat.category_id = '2' AND bk_cat.category_id = '1'

这不起作用，category_id不能同时为2和1。

您的查询应如下所示：

SELECT books.*
FROM books
  JOIN book_categories bc1 ON books.id = bc1.book_id AND bc1.category_id = 1
  JOIN book_categories bc2 ON books.id = bc2.book_id AND bc1.category_id = 2

您需要在类别上JOIN 两次，或者您需要匹配类别的次数。

Answer 2

有多种方法可以做到这一点，但最简单的方法是使用WHERE这样的SELECT条款到WHERE `bk`.`book_id` IN (SELECT `book_id` FROM `book_category` WHERE `category_id` = '2') AND `bk`.`book_id` IN (SELECT `book_id` FROM `book_category` WHERE `category_id` = '1') 本书，这些条款属于多个类别：

{{1}}