Thank you for answering Kumar. The parent table available_holidays holds the available holidays per year a user has e.g.

'01.01.2010;15;user'
'01.01.2011;20;user'

Since the dates in child table holidays are different eg. than parent year I don't know how to create constraints. e.g.

'15.07.2010;20.07.2010;user'
'03.03.2011;10.03.2011;user'