Why the sql query do not execute? - php

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

Answer 2

using single quotes in php may be the problem:
$sql = 'INSERT INTO delete_user_list SELECT * FROM user_list WHERE ListID=$id';
here, $id won't be resolved by php interpreter because of single quote which is 'raw string'
if you want $id to be resolved, use " (double quote)
$sql = "INSERT INTO delete_user_list SELECT * FROM user_list WHERE ListID=$id";
or use parameterized statements (preferred & much safer)
$sql = "INSERT INTO delete_user_list SELECT * FROM user_list WHERE ListID=?";
$stmt = $conn->prepare($sql);
$stmt->execute($id);

Answer 3

Which of the queries does not get executed? Can you check whether there is a connection at all (meaning are your credentials correct)?