my daughter whines all the time

Somewhere along the line, she learned that whining was the way to get what she wants. It really isn't that uncommon. Girls tend to be taught to whine, while boys learn to negotiate. Don't make fun of her. Don't threaten her. Simply don't reward the behavior, and that includes giving her attention for it. When she isn't in the process of whining, you can sit down with her and talk to her. Treat her like she is a real person. Talk to her as though you would an adult (using age-appropriate language, of course) regarding the situation.

Your child as I could imagine has something that bothers her that is why she always whines so that you could provide her some sort of affection and care to sooth her grief.The best way is ask her what is the matter so a proper solution could be given so that she would stop whining.It might be also that she was suffering some pain that she do not know how to tell you that is why asking her might give her the correct solution so that she could be diagnose to a doctor.