where caluse sql not working for me

where caluse sql not working for me

I am a beginner in sql. So please do not downvote my question. In my code
below, $i1 is a string and $l1 is also a string. The code is not working.
Any help will be appreciated. Thanks in advance. The following is my
code:-
$result = mysqli_query($con,"SELECT Ltno FROM Dept1_Selfin WHERE
Item='".$i1."' AND
Ltno='".$l1."'");