Question

This code is what i have tried to process the query, either delete or insert do not have affect.

The id is correct and conn.php is correct .

I just copy the sql query to phpmyadmin to test and it works.

And i put a echo "test"; between try{} it echo too.

Thank you

<?
include("../connection/conn.php");
session_start();

$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// list out the pervious create list
//$id=$_GET['id'];

$id=3;
try{
$sql = 'INSERT INTO delete_list SELECT * FROM list WHERE ListID=?';
$stmt = $conn->prepare($sql);
$stmt->execute(array($id));
}
catch(PDOException $e)
    {
    die ($e->getMessage().'<a href="view.php"> Back</a>'); 
    }

try{
$sql = 'INSERT INTO delete_user_list SELECT * FROM user_list WHERE ListID=?';
$stmt = $conn->prepare($sql);
$stmt->execute(array($id));
}
catch(PDOException $e)
    {
    die ($e->getMessage().'<a href="view.php"> Back</a>'); 
    }

try{
$sql = 'INSERT INTO delete_require_attributes SELECT * FROM require_attributes WHERE ListID=?';
$stmt = $conn->prepare($sql);
$stmt->execute(array($id));
}
catch(PDOException $e)
    {
    die ($e->getMessage().'<a href="view.php"> Back</a>'); 
    }

try{
$sql = 'INSERT INTO delete_subscriber SELECT * FROM subscriber WHERE ListID=?';
$stmt = $conn->prepare($sql);
$stmt->execute(array($id));
$count=$stmt->rowCount();
}
catch(PDOException $e)
    {
    die ($e->getMessage().'<a href="view.php"> Back</a>'); 
    }

try{
$sql = 'INSERT INTO delete_list_sub SELECT * FROM list_sub WHERE ListID=?';
$stmt = $conn->prepare($sql);
$stmt->execute(array($id));
}
catch(PDOException $e)
    {
    die ($e->getMessage().'<a href="view.php"> Back</a>'); 
    }


    try{
$sql = 'DELETE FROM list WHERE ListID = ?';
$stmt = $conn->prepare($sql);
$stmt->execute(array($id));
}
catch(PDOException $e)
    {
    die ($e->getMessage().'<a href="view.php"> Back</a>'); 
    }

echo "The list has been deleted.".$count." subscribers has been removed. <a href='view.php'> Back</a>";

?>

i added

$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

and error is

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'ListID' in 'where clause' Back

Answer 1

It doesn’t work because in order for variables to be interpolated you need to use double quotes (“) not single quotes. Single quotes makes it literally pass “$id” instead of the value.

But since you’re using PDO you should be using prepared statements! Like this:

$sql = 'INSERT INTO delete_list SELECT * FROM list WHERE ListID=?'
$stmt = $conn->prepare($sql)
$stmt->execute(array($id));

The value of $id replaces the ?

EDIT: fixed the parameter