Question

I have set dob as type “date” in my html and in my stu table i am taking it as a string so i have made it as varchar, but null is getting stored as default value

Check the code…

 /* Prepared statement, stage 1: prepare */
if (!($stmt = $mysqli->prepare("INSERT INTO `stu` (`name`, `gender` , `dob`) VALUES (
?, ?, ? ) "))) {
echo "Prepare failed: (" . $mysqli->errno . ") " . $mysqli->error;
}

/* Prepared statement, stage 2: bind and execute */

if (!$stmt->bind_param('sss', $name , $gender , $dob )) {
echo "Binding parameters failed: (" . $stmt->errno . ") " . $stmt->error;
}

Answer 1

The code you posted is OK (though we can’t see if you actually execute() the query). The problem is the code that we can’t see, where you define $dob.

When you pass $dob to bind_param() it should be a string, not an object or anything else that you might have. Format $dob as a string and that will enable it to be inserted into the table.

I also suggest changing your field to a DATE instead of a VARCHAR. Your varchar field will accept any string date format but a DATE field will need YYYY-MM-DD.