Html值空白但我分配了它

I have a form which fetches data from a DB and inserts it to a database, some values are inserted blank even though I actually set its values not to be blank and even the browser output shows there is no value to

Here is my code:

$search_disease = $_POST['tdisease'];
$disease = "(select * from medications WHERE diagnosis='$search_disease')";
foreach ($pdo->query($disease) as $row){  
    $diagnosis = $row['diagnosis']; 
    $icd = $row['ICD10']; 
}

i then echo the results to a select tag

<select  style="width: 40%; margin-left: -1%; position: relative;top: -52px; left: 15px;"  name="tdisease">
   <option value="">Select Disease1</option>
   <?php while ($row=$result->fetch_array(MYSQLI_ASSOC)) { ?>
       <option value="<?php echo !empty($icd)?$icd:'';?>"><?php echo $row['diagnosis'];?> </option> 
   <?php } ?> 
</select>
<input class="btn btn-warning" style="width: 170px; margin-left: 17%; margin-top: 15%; margin-bottom: 1%; color: #000;" type="submit" name="insertData" value="Create Invoice">

And this is what the browser outputs:

<select  style="width: 40%; margin-left: -1%; position: relative;top: -52px; left: 15px;"  name="tdisease">
    <option value="">Select Disease1</option>
    <option value="">Cholera due to Vibrio cholerae 01, biovar cholerae</option> 
    <option value="">Cholera due to Vibrio cholerae 01, biovar eltor</option> 
    <option value="">Cholera, unspecified</option>                            
</select>

What is the issue here?

You are echoing the diagnosis name but you are not echoing the ICD10 code in the value attribute of the option.

You should just do this: <option value="<?= !empty($row['ICD10'])?$row['ICD10']:'';?>"><?= $row['diagnosis'];?> </option>

The problem really is that in your while ($row=$result->fetch_array(MYSQLI_ASSOC)) loop, there is no assignment to the $icd variable.

OPTION 2: Change your first php code above to:

$diagnoses = [];
foreach ($pdo->query($disease) as $row){ 
  $diagnosis = []; 
  $diagnosis['diagnosis'] = $row['diagnosis']; 
  $diagnosis['icd10'] = $row['ICD10']; 

  $diagnoses[] = $diagnosis;
}

Then in the iteration part:

<?php foreach ($diagnoses as $disease) { ?>
   <option value="<?= !empty($disease['icd10'])?$disease['icd10']:'';?>"><?= $disease['diagnosis'];?> </option> 
 <?php } ?>