How make query and show data - php

Question

I try to do input number form and make search in page grapht.php. For example I write code:
<form action="grapht.php" method="post">
Name: <input type="text" name="number" autocomplete="off"><br>
<input type="submit">
</td>
</form>
<? $number= $_POST["number"]; ?>
And then make query my MySQL table:
$shipmin = 1;
$shipmax=$number;
$uzklausimas ="SELECT * FROM MyGuests WHERE id >= '$shipmin' AND id<= '$shipmax'";
$minmax=mysqli_query($conn,$uzklausimas);
while($ru=mysqli_fetch_assoc($minmax)){
echo "$ru[id] <br>";
}
But my code doesn't work. Maybe somebody could give me advice how need solve this my problem?

Answer 1

Do you initialize your db connection ($conn) before this line ?
$minmax=mysqli_query($conn,$uzklausimas);

Answer 2

if I write line $shipmax=45; it is working well, but I have static date from 1 to 45. If I write $shipmax=$number; It is not work.

Answer 3

all my code
<?php
$servername = "localhost";
$username = "xxxxx";
$password = "xxxx";
$dbname = "xxxxx";
$conn = mysqli_connect($servername, $username, $password, $dbname);
if (!$conn) {
die("Connection failed: " . mysqli_connect_error());
}
$shipmin = 1;
$shipmax=$number;
$uzklausimas ="SELECT * FROM MyGuests WHERE id >= '$shipmin' AND id<='$number'";
$minmax=mysqli_query($conn,$uzklausimas);
while($ru=mysqli_fetch_assoc($minmax)){
echo "$ru[id] <br>";
}
mysqli_close($conn);
?>
<form action="forum.php" method="post">
Name: <input type="text" name="name" autocomplete="off"><br>
<input type="submit">
</td></form>
<? $number= (int)$_POST["name"]; ?>
<?php echo $number; ?>
<br>
Page where you could see it is http://ortex.lt/forum.php