PHP / MySQL：获取特定ID的名称

Question

I am a beginner to MySQL and Im trying to retrieve a name for a specific ID.

Here is how my database looks like:

I have a table of contacts which contains ID, first and last name.

I want to retrieve the first and last name for a specific ID in the same form.

So I want to end up with a form of options and the option value will be the first name for each ID.

For example:

<form>
<select name="users">
<option value="">Select a person:</option>
<option value="5"> <?php echo "$first $last" ?> </option>
<option value="10"> <?php echo "$first $last" ?> </option>
<option value="15"> <?php echo "$first $last" ?> </option>
</select>
</form>

The values are the ID's.

and my PHP:

<?php   include("connection.php");

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

$num=mysql_numrows($result);

mysql_close();

$i=0;
while ($i < $num) {

$first=mysql_result($result,$i,"first");
$last=mysql_result($result,$i,"last");

$i++;
}

?>

in my actual example I get the first and last name of the last's person in the database only.

So how can I retrieve the first and last name for specific ID's of which I assign in my form (?)

Answer 1

This is because your while loop is overwriting $first and $last every single time. Try

$users = array();

while ($row = mysql_fetch_assoc($result)) { 
  $users[] = $row;
}

And in HTML (EDITED):

<form>
  <select name="users">
    <option value="">Select a person:</option>
    <?php foreach($users as $row): ?>
      <option value="<?php echo $row['id']; ?>"> <?php echo $row['first'] . " " .  $row['last']; ?> </option>
    <?php endforeach; ?>
  </select>
</form>

Answer 2

Assuming your contacts table has a primary key field, you'd use THAT field to put into your <option> tags as the value. Then you've got a 1:1 correspondence between a particular <option> and a record in the database. If you go by name alone, you'll end up (say) 5 "John Smith" entries and it would be impossible to tell which one you want.

So, make your query be:

SELECT id, firstname, lastname
FROM ...

and then:

    while ($row = mysql_fetch_assoc($result)) {
       echo <<<EOL
<option value="$row[id]">$row[firstname] $row[lastname]</option>

EOL;
    }

Answer 3

$users = $_POST['users'];
$query = 
"SELECT 
    ID, FIRSTNAME, LASTNAME 
FROM 
    CONTACTS 
WHERE 
    ID = '$users'";

Of course, while this works, it is a classic example of a SQL injection vulnerability. You'll want to either sanitize the input or use a prepared statement and binding variables.

Answer 4

You can do

$query="SELECT * FROM contacts WHERE id = '$id'";

A little googling will go a long way. Read this and this .