User form-data to update query PHP - php

Question

I have basic question about storing $variable data and later use in html script, anyone who can help me? Right now, the variable $gset is not stored.
<?php
// Update Strictness value
if(isset($_POST['strictness'])){
$gset = $_POST['strictness'];
$strictnessUpdate = "UPDATE users SET strictness = '$gset' WHERE user_id = 1";
mysqli_query($conn, $strictnessUpdate);
echo "strictness value updated";
}
?>
<form method="POST" class="form-align" action="">
<h5 class="my-6">Current Strictness :</h5> <?php echo $gset; ?><br>
<select name="strictness" required>
<option value=""></option>
<option value="15">15</option>
<option value="31">31</option>
</select>
<input type="submit" name="substrict" value="CHANGE">
</form>

Answer 1

<?php
$_grabStrictness ="SELECT strictness FROM users WHERE id = 1";
$gs_query = mysqli_query($conn, $_grabStrictness);
$gs_result = mysqli_fetch_array($gs_query);
if ($gs_result > 0) {
while ($result = mysqli_fetch_array($gs_query)) {
$gset = $result['strictness'];
}
}
if(isset($_POST['strictness'])){
$gset = $_POST['strictness'];
$strictnessUpdate = "UPDATE users SET strictness = '$gset' WHERE user_id = 1";
mysqli_query($conn, $strictnessUpdate);
echo "strictness value updated";
}
?>
<form method="POST" class="form-align" action="setStrictness(<?php $conn ?>)">
<h5 class="my-6">Current Strictness :</h5> <?php echo $gset; ?><br>
<select name="strictness" required>
<option value=""></option>
<option value="15">15</option>
<option value="31">31</option>
</select>
<input type="submit" name="substrict" value="CHANGE">
</form>