如何删除数据库中的多条记录

Question

我想创建一个按钮来删除所有需要删除的记录。我的数据库 person、address 和 cv 中有三个表... address_id 与 person 表中的 person_address 有关系，而 cv_id 与 person 表中的 person_cv 有关系。按下删除按钮时，应删除与此人相关的所有内容。我尝试了很多方法，例如：

 echo "<td><a href='delete.php?id=<?" . $row['id'] . "'>delete</a></td>";

使用外部 delete.php 但它根本不起作用...link 在链接中我用于 delete.php 的教程

我的详细信息页面，删除按钮应该在 CV 之后：

<?php
$servername = "localhost";
$username = "root";
$password = "usbw";
$dbname = "persons";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
} 

$sql = "SELECT person_firstname, person_lastname, 
           person_email, person_phonenumber,  
           address_street,address_housenumber, 
           address_city,address_state,address_zipcode, cv_path
    FROM person 
       inner join address on address.address_id = person.person_address 
       inner join cv on cv.cv_id = person.person_cv";

$result = $conn->query($sql);
if ($result->num_rows > 0) {

  echo "<table border=1>
  <tr>
  <th>Voornaam</th>
  <th>Achternaam</th>
  <th>Straat</th>
  <th>Huisnummer</th>
  <th>Postcode</th>
  <th>Stad</th>
  <th>Provincie</th>
  <th>Email</th>
  <th>Mobiel</th>
  <th>CV</th>
  </tr>";


while($row = $result->fetch_assoc()) {
    echo "<tr>";
    echo "<td>" . $row["person_firstname"] . "</td>";
    echo "<td>" . $row["person_lastname"] . "</td>";
    echo "<td>" . $row["address_street"] . "</td>";
    echo "<td>" . $row["address_housenumber"] . "</td>";
    echo "<td>" . $row["address_zipcode"] . "</td>";
    echo "<td>" . $row["address_city"] . "</td>";
    echo "<td>" . $row["address_state"] . "</td>";
    echo "<td>" . $row["person_email"] . "</td>";
    echo "<td>" . $row["person_phonenumber"] . "</td>";
    echo "<td><a href='http://localhost:8080/website/" . $row['cv_path'] . "'>cv file</a></td>";
    echo "</tr>";
}
}
else {
echo "Er is niks in het database gevonden";
}
$conn->close();
?> 

删除.php：

<?php

$host="localhost"; // Host name 
$username="root"; // Mysql username 
$password="usbw"; // Mysql password 
$db_name="persons"; // Database name 
$tbl_name="person"; // Table name 

// Connect to server and select databse.
mysql_connect("$host", "$username", "$password")or die("cannot connect"); 
mysql_select_db("$db_name")or die("cannot select DB");

// get value of id that sent from address bar 
$id=$_GET['person_id'];

// Delete data in mysql from row that has this id 
$sql="DELETE FROM $tbl_name WHERE person_id='$id'";
$result=mysql_query($sql);

// if successfully deleted
if($result){
echo "Deleted Successfully";
echo "<BR>";
echo "<a href='admin.php'>Back to main page</a>";
}

else {
echo "ERROR";
}
?> 

<?php
// close connection 
mysql_close();
?>

Answer 1

有两种方法：

1. 从所有 3 个表中手动删除。以下是对此的查询：

   delete prsn, addr, cv from person prsn join address addr on p.person_address = addr.address_id join cv cv on prsn.person_cv = cv.cv_id where prsn.id = ?

2. 以这样的方式创建外键约束，一旦父记录被删除，子记录就会自动被删除。例如。像这样重新创建地址表：

   create table address( ... FOREIGN KEY (address_id) REFERENCES person(person_Address) ON DELETE CASCADE );

然后，我们只需要执行以下查询：

delete from person where id = ?

Answer 2

我从屏幕截图中看到您已经在使用InnoDB 表，因此使用person_id 作为引用列在address 和cv 表上设置一些外键依赖项应该不会太难。

作为使用外键来实现 rippled delete 的示例，这似乎是导致问题的三个表，它们具有外键依赖集 - 这样您就可以从 person 表中删除 ~ 使用 @987654327此人的@ 以及相关表中的所有记录也将被删除。

create table if not exists `person` (
  `id` int(10) unsigned not null auto_increment,
  `name` varchar(50) not null,
  primary key (`id`)
) engine=innodb auto_increment=2 default charset=latin1;

create table if not exists `address` (
  `id` int(10) unsigned not null auto_increment,
  `person_id` int(10) unsigned not null default '0',
  `address` varchar(50) not null default '0',
  primary key (`id`),
  unique key `person_id` (`person_id`),
  constraint `fk_user_address` foreign key (`person_id`) references `person` (`id`) on delete cascade on update cascade
) engine=innodb auto_increment=2 default charset=latin1;

create table if not exists `cv` (
  `id` int(10) unsigned not null auto_increment,
  `person_id` int(10) unsigned not null default '0',
  `cv` varchar(50) not null default '0',
  primary key (`id`),
  key `person_id` (`person_id`),
  constraint `fk_user_cv` foreign key (`person_id`) references `person` (`id`) on delete cascade on update cascade
) engine=innodb auto_increment=2 default charset=latin1;

/* dummy data */
insert into `person` (`id`, `name`) values (1, 'bobby');
insert into `address` (`id`, `person_id`, `address`) values (1, 1, '99 riverside drive, dundee');
insert into `cv` (`id`, `person_id`, `cv`) values (1, 1, 'bobby_cv.docx');


/* this is how the tables look */    
person table
+----+-------+
| id | name  |
+----+-------+
|  1 | Bobby |
+----+-------+

address table
+----+---------------+----------------------------+
| id | person_id(fk) | address                    |
+----+---------------+----------------------------+
|  1 |         1     | 99 Riverside Drive, Dundee |
+----+---------------+----------------------------+

cv table
+----+---------------+---------------+
| id | person_id(fk) | cv            |
+----+---------------+---------------+
|  1 |         1     | bobby_cv.docx |
+----+---------------+---------------+

在这种情况下，要删除与 Bobby 关联的所有记录，sql 可以简单地为：

delete from `person` where `id`=1;

如果不使用这样的外键，您将需要为每个要删除用户及其关联记录的表构建单独的 sql 语句。

即：

delete from person where person_id=X;
delete from address where person_id=X;
delete from cv where person_id=X;

---

更新

抱歉延迟响应 - 已调用睡眠。

在您的 sql SELECT 语句中，用于显示用户以及来自其他表的相关详细信息，您没有选择 person_id 这是使删除语句​​起作用所需的关键（双关语）元素。

$sql = "SELECT person_id, person_firstname, person_lastname, 
       person_email, person_phonenumber,  
       address_street,address_housenumber, 
       address_city,address_state,address_zipcode, cv_path
FROM person 
   inner join address on address.address_id = person.person_address 
   inner join cv on cv.cv_id = person.person_cv";

那么，在while 循环中

while($row = $result->fetch_assoc()) {
    $person_id=$row['person_id'];
    /* etc - other content as before */

    /* note the parameter used is "ID" */
    echo "<a href='delete.php?id={$person_id}'>Delete</a>";
}

然后在 delete.php 中提供 FK 依赖项已设置（这完全取决于您如何完成这些）

/* options used to ensure supplied id is within acceptable bounds */
$options = array(
    'options' => array(
        'default' => 0,
        'min_range' =>  1,
        'max_range' =>  10000000 /* maximum value for ID */
    )
);

/* process GET parameters - notably "ID" */
$id=filter_input( INPUT_GET, 'id', FILTER_SANITIZE_NUMBER_INT );
$id=(int)filter_var( $id, FILTER_VALIDATE_INT, $options );

/* construct & execute sql */
if( is_int( $id ) ){
    $sql="delete from `person` where `id`='{$id}';";

    $result=mysql_query( $sql );
}

一个未解决的问题是 sql 注入。原始代码和我在这里详述的代码都使用现已弃用的mysql_* 系列函数，并且容易受到sql 注入的影响。一旦你发现了这个删除问题，将你的代码迁移到使用mysqli是谨慎的，这样你就可以使用prepared statements