Unfortunately, databases do not understand full sentences and are not always like Google. In Google I can type, "What's the weather like in Vancouver this weekend?" and I will receive the answer. You need to dumb down your inquiry to short, important pieces of information.
I.E.: Vancouver / Weather / August 8 2015
Once you have the meat (key concepts) of your inquiry figured out, you can then start to put together a search strategy; which is where the Boolean Search Terms come in hand (see image below). You should consider synonyms as well. Perhaps others refer to dogs as canines in their article or specifically the breed German Shepard. You want to make sure you get ALL of the relevant possibilities for your research.