如何查询关系Table中的所有结果？

Question

在一个查询中，我 SELECT 来自书籍 Table 的特定产品数据。像标题、作者、年份等。我想得到它的所有作者，但它 只显示 第一个 .

产品Table：

produto
   idproduto
   sku
   titulo
   others not important

作者 Table:

autor
   id_autor
   nome_autor

关系型 Table:

    autorxprod
        idautoria
        idprod (FK)
        idautor (FK)

如何显示与 Book1 相关的所有作者？？我应该在主 QUERY 中创建另一个 QUERY 吗？？

用代码编辑。我评论了一点，因为它是用葡萄牙语写的

$produto = $_GET['sku']; 
$idproduto = $_GET['idprod'];

$query = "SELECT 

p.titulo AS titulo, p.imgprod AS imgprod, p.marca AS idmarca, p.sku AS sku,
p.prodcateg AS prodcateg, p.ano AS ano, p.titeng AS titeng,
p.codbarra AS codbarra, p.desc AS descricao, // product infos

c.idcategoria AS idcategoria, c.nomecateg AS nomecateg, // category infos
m.nome_marca AS nome_marca, // brand info

a.nome_autor AS nome_autor, // author info
a.id_autor AS idautor   // author id

FROM (produto p, autor a)

   LEFT JOIN categoria c // category join
   ON p.prodcateg = c.idcategoria

   LEFT JOIN marcas m // brand join
   ON p.marca = m.id_marca  

   LEFT JOIN autorxprod axp // relational table
   ON p.idproduto = axp.idprod
   AND a.id_autor = axp.idautor


   WHERE p.sku LIKE '$produto'";

   $result = $conn ->query ($query);


if (!$result) die ($conn->error);

$rows = $result->num_rows;  

    for ($j = 0; $j <$rows; ++$j)
    {
        $result -> data_seek($j);
        $row = $result->fetch_array (MYSQLI_ASSOC);?>

 -----------

 <?php echo $row['nome_autor']?>

Answer 1

我不认为这是错误的，但是您的 sql 在混合连接样式方面有点奇怪。我可以建议这个吗：

SELECT 
  p.titulo AS titulo, p.imgprod AS imgprod, p.marca AS idmarca, p.sku AS sku,
  p.prodcateg AS prodcateg, p.ano AS ano, p.titeng AS titeng,
  p.codbarra AS codbarra, p.desc AS descricao, // product infos

  c.idcategoria AS idcategoria, c.nomecateg AS nomecateg, // category infos
  m.nome_marca AS nome_marca, // brand info

  a.nome_autor AS nome_autor, // author info
  a.id_autor AS idautor   // author id

FROM produto p
LEFT JOIN categoria c  ON p.prodcateg = c.idcategoria
LEFT JOIN marcas m  ON p.marca = m.id_marca  
LEFT JOIN autorxprod axp ON p.idproduto = axp.idprod
JOIN autor a ON a.id_autor = axp.idautor
-- above is what your code did, you could also use a left join like this and you might have null authors
-- LEFT JOIN autor a ON a.id_autor = axp.idautor
WHERE p.sku LIKE '$produto'

Answer 2

我可能弄错了，但在我看来，您可能想要运行两个单独的查询。一个查询获取与搜索相匹配的书籍，第二个查询获取该书的所有作者。因为关系 table 是多对一的，所以如果您尝试加入 table s，您最终会得到一个结果集，其中多次列出同一本书，每个作者一个。那是你想要的吗？

如果我弄错了，而您确实希望每本书有多个记录，这里是您需要的连接查询的简化版本。

SELECT 
 p.titulo AS titulo
 a.nome_autor
FROM 
 author a,
 produto p
 LEFT JOIN autorxprod axp
 ON  axp.idprod =p.idproduto 
WHERE 
 p.sku LIKE '$produto'
 AND  axp.idautor = a.id_autor

Answer 3

感谢所有耐心等待我的人，因为我正在学习我真的迷路了。这是我需要的完成结果，它按预期工作。比以前简单多了。

此代码获取相关产品的所有作者并显示为作者 1、作者 2、作者 3...

"SELECT     
            ....get stuff...

            a.id_autor AS idautor,
            GROUP_CONCAT(DISTINCT a.nome_autor ORDER BY a.nome_autor SEPARATOR ', ') AS autor_list


        FROM 

        produto p

        LEFT JOIN categoria c
        ON p.prodcateg = c.idcategoria  

        LEFT JOIN marcas m
        ON p.marca = m.id_marca     

        LEFT OUTER JOIN (autor a, autorxprod axp)
        ON axp.idautor = a.id_autor AND
        axp.idprod = '$produto'


        WHERE
        p.sku = '$produto'

如何查询关系Table中的所有结果？

How query all results in a Relational Table?

mysql

sql

select

foreign-key-relationship