submit form data to wordpress existing database table using my plugin

I think I found out where the problem was. the datatype for check_in and check_out in the database was set to DATETIME Instead of DATE yet the code $check_in_db=date("Y-m-d",strtotime($check_in)); was converting it to date. I don’t know why it prevented entry of the other data, but after changing that, it is working now.
to use date time, use this $check_in_db=date("Y-m-d H:i:s",strtotime($check_in));