REMEMBER! Business research is different from other disciplines--it has many facets and you will need to use several resources to get a complete picture. There is no "magic database" that will have everything you need in one place.
Most business research requires both primary and secondary research.
Primary research is new research, carried out to answer specific issues or questions. It can involve questionnaires, surveys or interviews with individuals or small groups.
Secondary research makes use of information previously researched for other purposes & publicly available. Market research reports, articles, demographics--any information NOT INITIALLY COLLECTED by you. Library resources are secondary research.
Read "The Difference Between Primary and Secondary Research" (The Balance: Small Business) for more information.