Question

我有两张桌子，一张是书，另一张是书。它们通过一对多关系相关联，即编写器中的主键，即w_id是由b_writer命名的书中的外键。但是当我在php脚本中打印b_writer时，它会打印id，即一个数字，但我想要写作者的名字。我该怎么办？

$connect = mysqli_connect("localhost", "root", "", "ecom");  
$query = "SELECT * FROM books WHERE b_id = '".$_POST["book_id"]."'";  
$result = mysqli_query($connect, $query);
    while($row = mysqli_fetch_array($result))  
{  
    echo $row["b_id"] $row["b_desc"] $row["b_name"] $row["b_writer"];
}

打印b_writer时，如何打印作者姓名。

Answer 1

您应该使用连接来获取表格中的数据，例如：

"SELECT b.*, w.* 
 FROM books as b
 INNER JOIN writer as w on b.b_writer = w.w_id
 WHERE b_id = '".$_POST["book_id"]."'";

但请注意在查询中使用var，否则会面临sqlinjection风险

为了避免这种情况您应该使用prepare语句和绑定参数，例如：

$stmt = $db->prepare("SELECT b.*, w.* 
  FROM books as b
  INNER JOIN writer as w on b.b_writer = w.w_id
  WHERE b_id =?");
$stmt->bind_param("i",$_POST["book_id"] );
$stmt->execute();

Answer 2

使用join

更改您的查询

select a.*,b.* from book as a inner join writer b on a.b_id = b.id where b_id = '".$_POST["book_id"]."'

显示来自php

2 个答案: