Boolean Logic & Other Database Search Tips
Boolean search terms allow us to filter our search results so we are more likely to find the websites that are useful to us. The basic Boolean search terms are:
- AND - which combines two or more keywords/phrases (e.g. apples AND oranges)
- NOT - which removes specific keywords/phrases (e.g. fruit NOT oranges)
- OR - which shows combined results for two or more keywords/phrases (e.g. apples OR oranges)
- "___" - which searches for a specific phrase (e.g. "apple pie")
https://www.lotame.com/what-is-boolean-logic/
Click here for a simple visualization of what Boolean operators do to search results.
Search Operator Cheat Sheet
Operator | Effect | Notes |
AND | Strongly restricts search results | Engines use + |
NOT | Restricts search results | Engines use - |
OR | Expands search results | Engines & databases |
(nesting) | Words in brackets go first | Both use |
“phrase searching” | Searches for exact phrase | Both use |
? | Replaces one letter anywhere | Databases only |
* | Changes end of word | Databases only |
inurl:(no space) | Searches for pages with this in address | Engines only |
intitle:(no space) | Searches for pages with this in title | Engines only |
filetype:(no space) | Searches for a certain file type, e.g. PDF only | Engines only |
link:(no space) | Counts how many sites are linked to this one | Engines only |
1. When you search a database and do not get the results you expect, ask for help. is here to help you.
2. Start with a keyword search, using words/phrases that describe your topic.
3. Browse the results; choose 2 or 3 that are relevant.
4. Look at the Subject Headings and note the terms used (write them down).
5. Redo your search using those terms, your results will be more precise than your initial keyword search.
6. Use truncation, enter the root of a word and put the truncation symbol at the end to broaden your search.
genetic* = genetic, genetics, genetically
Truncation symbols may vary by database; common symbols include: *, !, ?, or #.
7. Consider using limits to limit to document type, date range, language, etc.
8. Use Boolean operators: AND, OR, NOT.
9. Track your MLA Citations.