Through boolean operators (And,Or,Not)
Boolean logic is considered to be a well known search strategy used in search engines and in databases; it helps the user to narrow and broaden his search to get accurate information.
Aand: is used to narrow the search and retrieve records containing all of the terms (both words) mentioned in the search.
Example: Library services AND Marketing.
Or: It broadens the search and retrieves results containing any (or both )of the words mentioned in the search
Example: Management OR Administration.
Not: Narrow the search and retrieve records that do not contain the term following it.
Example: Medicine NOT Herbal medicine.