为什么我的下拉列表没有填充表格数据？

Question

WHy is my drop down list not populating with the table data? (dropdown box is empty) And what is used to display data upon selection of an item in that drop down - is it a "VIEW" (please do provide a study link so I can learn)

My Code

<?php
$con=mysqli_connect("localhost","root","","ismat_db");
//check connection
if(mysqli_errno($con))
{
echo "Can't Connect to mySQL:".mysqli_connect_error();
}
else
{
echo "Connected to mySQL</br>";
}

 //$query = 'SELECT FirstName FROM persons';
//$result = mysqli_query($con,$query);

$query = mysqli_query($con,"SELECT 'FirstName' FROM persons");

//print_r($query);

//echo '<select name="FirstName">';
echo "<select name= 'FirstName'>";
//while($row=mysqli_fetch_array($result))
while($row=mysqli_fetch_array($query))
{
echo $row;
//echo "<option value='".$row['FirstName']."'>".'</option>';
}
echo '</select>';

?>

Answer 1

Try this:

echo "<option value='".$row['FirstName']."'>".$row['FirstName']."</option>";

Also seems that you are having an issue with the database query. Swap your while loop with the following and see if it works

if ($result = $mysqli->query($query)) {

    while ($row = $result->fetch_assoc()) {
    echo "<option value='".$row['FirstName']."'>".$row['FirstName']."</option>";
    }

$result->free();
}

Answer 2

You had 2 errors:

I pointed the first in the comment: to print an option you must use this code:

echo "<option value='". $row['FirstName']."'>".$row['FirstName']
 . '</option>';

The second is in your SQL: you are not selecting the FirstName field from the database, but a string 'FirstName' instead. That's why it is printed twice as you said. Use this SQL to get the field:

$query = mysqli_query($con,"SELECT FirstName FROM persons");

---

Also usually people put an id of the record and not a field, that may have possible duplicates into the value of an <option> . So, I would have used:

echo "<option value='". $row['id']."'>".$row['FirstName']
 . '</option>';

selecting the id from the database together with first name.