删除行mysql php

Question

Using the following code:

if (isset($_POST['delete']) && isset($_POST['id']))
{
    $first = get_post('first');
    $query = "DELETE FROM user_master WHERE id='$id'";
    if(!mysql_query($query, $db_server))
        echo "DELETE failed: $query<br />" . 
        mysql_error() . "<br /><br />";
}

$query="SELECT * FROM user_master";
$result= mysql_query($query);

if(!result) die ("Database access failed: " . mysql_error());
$rows = mysql_num_rows($result);

for ($j=0 ; $j<$rows ; ++$j)
{
    $row = mysql_fetch_row($result);
    echo <<<_END
    <pre>
    ID      $row[0]
    First   $row[1]
    Last    $row[2]
    Email   $row[3]
    User    $row[4]
    </pre>
    <form action="willingLog.html" method="post">
    <input type="hidden" name="delete" value="yes" />
    <input type="hidden" name="id" value="$row[0]" />
    <input type="submit" value="DELETE RECORD" /></form>
_END;

I'm unable to delete a record form the table.

All the records form the table are printing on the screen, including the "DELETE RECORD" button. When I hit the button, however, nothing happens. I've checked the actual table on phpmyadmin, and the table is unaffected as well.

I'm pulling this stuff from a book, so I don't understand why it's not working.

Answer 1

I do not see where you set the $id variable.

if (isset($_POST['delete']) && isset($_POST['id']))
{
    //$first = get_post('first');   #not sure what this does
    $id = sanitize($_POST['id'], 'int');  //protect from sql injection
    $query = "DELETE FROM user_master WHERE id=$id";
    if(!mysql_query($query, $db_server))
        echo "DELETE failed: $query<br />" . 
        mysql_error() . "<br /><br />";
}

Please be sure to sanitize any data sent across the network, ie $_POST . Also, if id is of a number type, do not surround the value in quotes or mysql will interpret it as a string.

Lastly, look into using MySqli or PDO , as MySql API has been deprecated.

Answer 2

Here i defined a variable from that variable i delete the values

$id = 2;

    $query = mysql_query("DELETE FROM table_name WHERE id="'.$id.'"");

note: Delete query id is important otherwise it delete whole rows defaulty.

Answer 3

$ query = mysql_query（“从表名删除，其中id = 1”）;

Answer 4

$query = "DELETE FROM user_master WHERE id='$id'";

This should probably be:

$query = "DELETE FROM user_master WHERE id='" . $_POST['id'] "'";

But please do some research into SQL injection, and why you should never pass information directly from the user into the database.

Answer 5

code should read:

$id = get_post('id');

in the first line of the curly braces under the first "if" statement.