用php读取mysql并在下拉菜单中显示结果

Question

i'm farly new to php and are trying to make a php script where it's suppose to connect to a mysql db and get the vaule id, then show as an option in a drop down menu.

This is the code I have so far (got help from a friend):

$username = "root";
$password = "";
$hostname = "localhost"; 
$database = "customers";
$id = "";

mysql_connect("$hostname", "$username", "$password") or die (mysql_error()) or die (mysql_error());

mysql_select_db("$database") or die (mysql_error());

$result = mysql_query("SELECT id FROM users WHERE id='$id'") or die(mysql_error());
      while ($row = mysql_fetch_assoc($result)) {
       $valuestring = $row['id'];
       print_r($result);
          echo "<option value='$valuestring'>". $valuestring ."</option>";
          mysql_close();
      }
print_r($id);

But when I use this code the option is returned empty :/

I have also tried to do print_r($result); and that give me Resource id #4, so I guess that works.

If anyone could help me solve this I would be one happy guy :D

Answer 1

the $id value in your code is empty, are you avare of that ? and can you print the query before sending it to mysql ? use :

"$query = "select id from table where id = '$id'";
mysql_query($query);
echo $query;

Answer 2

Perhaps if you showed us what output you did get it would help.

the option is returned empty

If the output includes HTML generated inside the loop then that means the query returned at least 1 row. But the only way that echo "<option value='$valuestring'>" would produce an empty string is if $valuestring was an empty string. It's populated from "SELECT id FROM users WHERE id='$id'" implying that you must have a row in your database where id is null or an empty string and $id in your php code is null/empty string - indeed that is the case ($id = "";).

NTW the mysql_close(); should be outside the loop.

Answer 3

Let's simplify this code:

<select name="user" id="user" width="200px" style="width: 200px">
<option value="">Select State</option>
<?php       
$query_uf =  "SELECT id FROM users WHERE id="'.$id.'";      
$result = mysql_query($query_uf,$bd);       
while ($users =mysql_fetch_assoc($result)) {
echo "<option value='".$uf['id']."'>".$uf['user']."</option>";      } 
?>
</select>

Obs: It's better you use mysqli_query and connect. And, in your code it's missing the connection in mysql_query.

Answer 4

I've previously needed to retrieve a list of albums from a table using a similar method, maybe try this function. Create your form and call the function within the and tags leading this to work. This should list your id(s) where specified in the query.

functions.php (or wherever you'd like to put the function):

function stateList() {
$username = "username"; 
$password = "password"; 
$host = "localhost"; 
$dbname = "dbname"; 
$id = RETRIEVE VALUE HERE;
$options = array(PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8'); 
$db = new PDO("mysql:host={$host};dbname={$dbname};charset=utf8", $username, $password, $options); 
$query = " 
    SELECT 
    id,
    FROM users 
    WHERE
    id = $id // YOU MAY WANT TO REMOVE WHERE - $ID AS STATED ABOVE, DOESN'T MAKE SENSE.
    "; 

    try 
    { 
        $stmt = $db->prepare($query); 
        $stmt->execute(); 
    } 
    catch(PDOException $ex) 
    { 
        die("Failed to run query: " . $ex->getMessage()); 
    } 
        $valuestring = $row['id'];
    $rows = $stmt->fetchAll(); 
foreach($rows as $row):
    print "<option value='" . $valuestring . "'>" . $valuestring . "</option>";
endforeach;
}
?>

Selection page:

<? include 'functions.php' ?> <!-- This will allow you to call the function. -->
<form action="example.php" method="post" enctype="multipart/form-data">
    <select name="album">
        <? stateList(); ?> <!-- Calls the function and retrieves all options -->
    </select>
    <input type="submit" name="submit" value="Submit">
    </form>