Question

我有一个包含许多表的数据库。在第1面，我有一个按钮，将我传到第2侧。在第2面，我希望代码删除每个命名表中的每一行，这些行具有我存储在变量中的特定pid。我在第2面有一个代码，但它没有做任何事情。

第2面的代码：

$pid3 = $_POST['pid2'];

$del = "DELETE FROM answer_det WHERE pid='$pid3'";
$del .= "DELETE FROM project WHERE pid='$pid3'";
$del .= "DELETE FROM question WHERE pid='$pid3'";
$del .= "DELETE FROM respondent WHERE pid='$pid3'";
$del .= "DELETE FROM result WHERE pid='$pid3'";
$del .= "DELETE FROM users WHERE pid='$pid3'";

$run = mysqli_query($mysqli,$del);

if($run)
{
   echo "<h1>Project is deleted!</h1>";
}

Answer 1

使用mysqli_multi_query

$pid3 = $_POST['pid2'];

$del = "DELETE FROM answer_det WHERE pid='$pid3';";
$del .= "DELETE FROM project WHERE pid='$pid3';";
$del .= "DELETE FROM question WHERE pid='$pid3';";
$del .= "DELETE FROM respondent WHERE pid='$pid3';";
$del .= "DELETE FROM result WHERE pid='$pid3';";
$del .= "DELETE FROM users WHERE pid='$pid3';";

$run = mysqli_multi_query($mysqli,$del);

if($run)
{
   echo "<h1>Project is deleted!</h1>";
}

Answer 2

您可以考虑更改存在pid的mysql表，以将该字段作为在删除时级联的外键。像

这样的东西

ALTER TABLE `answer_det` 
ADD FOREIGN KEY (pid) 
REFERENCES table_where_pid_is_the_primary_key (pid)
ON DELETE CASCADE;

将answer_det替换为其他表名，以便在那里创建密钥。如果您无权更改表格，那么您的查询可能会失败，因为您缺少分号来分隔它们：

$del = "DELETE FROM answer_det WHERE pid='$pid3';";
$del .= "DELETE FROM project WHERE pid='$pid3';";
$del .= "DELETE FROM question WHERE pid='$pid3';";
$del .= "DELETE FROM respondent WHERE pid='$pid3';";
$del .= "DELETE FROM result WHERE pid='$pid3';";
$del .= "DELETE FROM users WHERE pid='$pid3';";

Answer 3

或者，你可以运行一个带有连接的查询，如下所示：

$pid3 = $_POST['pid2'];

$del = "DELETE a,b,c,d,e,f FROM answer_det a "
$del .= "JOIN project b on b.pid=a.pid "
$del .= "JOIN question c  on c.pid=a.pid "
$del .= "JOIN respondent d on d.pid=a.pid "
$del .= "JOIN result e on e.pid=a.pid "
$del .= "JOIN users f on f.pid=a.pid "
$del .= "WHERE a.pid='$pid3'";

$run = mysqli_query($mysqli,$del);

if($run)
{
   echo "<h1>Project is deleted!</h1>";

}

How to delete from multiple tables in MySQL?

Answer 4

简化您的查询，如下所示

$pid3 = $_POST['pid2'];    
 $del= DELETE FROM answer_det 't1',project 't2',question 't3' USING t1, t2,t3 WHERE t3.pid = t2.pid and t1.pid = t2.pid AND t1.pid =  $pid3
$run = mysqli_query($mysqli,$del);
if($run)
{
echo "<h1>Project is deleted!</h1>";
}

参考。 delete rows from multiple tables

Answer 5

There是一个很好的解决方案：

DELETE t1, t2 FROM t1 INNER JOIN t2 INNER JOIN t3 WHERE t1.id=t2.id AND t2.id=t3.id;

Answer 6

您在查询结尾处缺少分号。你需要把＆＃39 ;;＆＃39;在每次查询之后，为了一起执行多个查询。

试试这个：

$pid3="1";

$del = "DELETE FROM answer_det WHERE pid='$pid3';";
$del .= "DELETE FROM project WHERE pid='$pid3';";
$del .= "DELETE FROM question WHERE pid='$pid3';";
$del .= "DELETE FROM respondent WHERE pid='$pid3';";
$del .= "DELETE FROM result WHERE pid='$pid3';";
$del .= "DELETE FROM users WHERE pid='$pid3';";

echo $del

通过php运行许多mySQL查询

6 个答案: