The problem is in insert query.If we insert a single data in the db it is inserted for multiple time in that the primary key(auto increment) is increased but the value give by the user didn't store in db why?
<html>
<head>
<title>comment</title>
</head>
<body>
<?php
require('db.php');
?>
<form action="db.php" method="get">
<input type="textarea" name="textarea" rows="4" value="" >
<input type="submit" name="submit" value="submit">
</form>
<?php
$comment = isset($_GET['textarea']) ? $_GET['textarea'] : '';
$sql="INSERT INTO comment(comments) VALUES('$comment')";
mysqli_query($con,$sql);
?>
</body>
</html>
the actual table name is comment and the column name is comment_id and comments. if a user ask some question in textarea(in HTML design) that should be inserted in comments column.