private void ClearDB()
{
courseDbSet.RemoveAll();
courseDbSet.setIncrementBack("course", 1);
labsDbset.RemoveAll();
labsDbset.setIncrementBack("lab", 1);
lecDbSet.RemoveAll();
lecDbSet.setIncrementBack("lecturer", 1);
taskDoneDbSet.RemoveAll();
taskDoneDbSet.setIncrementBack("taskDone", 1);
taskDbSet.RemoveAll();
taskDbSet.setIncrementBack("task", 1);
presentDbSet.RemoveAll();
presentDbSet.setIncrementBack("present", 1);
studDbSet.RemoveAll();
studDbSet.setIncrementBack("student", 1);
labdatesDbSet.RemoveAll();
labdatesDbSet.setIncrementBack("labdate", 1);
}