A database will look for results that contain the exact words that you enter into the search bar, similar to the Ctrl+F shortcut.
Databases typically run these searches in the information used to describe source. Unless the HTML text of the entire source is available, a database will not necessarily search the entire text of a source. For example, some databases will typically look for word matches in the title, abstract (summary), and the tagged subjects (hashtags) field of an article. Ultimately, you are banking on an author having used your exact wording somewhere or that this wording is present in the information about a source.
Because of this, searching for an entire question or statement isn't very effective for your research.
Instead:
Learn how you can "squeeze research questions" to pinpoint keywords in the following video.
There are some other strategies you can use with keywords to help refine your searches a bit more.
Africa* = Africa, African, Africanism, etc.
You do have to be careful with truncation. Sometimes you might get unexpected results.
Learn how to combine your keywords with Boolean operators AND, OR, and NOT; search for phrases, and find different word variations in the following video.
"Online Research: Tips for Effective Search Strategies" (3:04) by Sarah Clark is licensed under CC BY-NC-ND 4.0.