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Database Search Tips
- The key to being a savvy online searcher is to use common search techniques that you can apply to almost any database, including article databases, online catalogs and even commercial search engines.
- This is important because searching library databases is a bit different from searching Google.
- The techniques described in this section will enable you to quickly retrieve relevant information from the thousands of records in a database.
- When you search a database and do not get the results you expect, ask us for advice. Library staff are happy to help you find what you need.
Content created by MIT Libraries, adapted under the Creative Commons Attribution Non-Commercial License.
Boolean operators form the basis of mathematical sets and database logic.
- They connect your search words together to either narrow or broaden your set of results.
- The three basic boolean operators are: AND, OR, and NOT.
Why use Boolean operators?
- To focus a search, particularly when your topic contains multiple search terms.
- To connect various pieces of information to find exactly what you're looking for.
second creation (title) AND wilmut and campbell (author) AND 2000 (year)
What to look for
Root words that have multiple endings. Example: sun = suns, sunshine, sunny, sunlight
Words that are spelled differently, but mean the same thing. Example: color, colour
Truncation/wildcard symbols vary by database. Check the help screens to find out which symbols are used.
Truncation, also called stemming, is a technique that broadens your search to include various word endings and spellings.
- To use truncation, enter the root of a word and put the truncation symbol at the end.
- The database will return results that include any ending of that root word.
child* = child, childs, children, childrens, childhood
genetic* = genetic, genetics, genetically
- Truncation symbols may vary by database; common symbols include: *, !, ?, or #
Similar to truncation, wildcards substitute a symbol for one letter of a word.
- This is useful if a word is spelled in different ways, but still has the same meaning.
wom!n = woman, women
colo?r = color, colour
If you have questions about applying this technique to your search, Ask Us!
What to look for
To find subject headings for your topic:
- Look to see if the database has an online thesaurus to browse for subjects that match your topic (check the Help screens).
- Some databases publish thesauri in print (e.g. Thesaurus of Psychological Index Terms for the PsycInfo database).
Another way to find subject headings:
- Start with a keyword search, using words/phrases that describe your topic.
- Browse the results; choose 2 or 3 that are relevant.
- Look at the Subject or Descriptor field and note the terms used (write them down).
- Redo your search using those terms.
- Your results will be more precise than your initial keyword search.
What are subject headings and keywords?
Subject headings describe the content of each item in a database. Use these headings to find relevant items on the same topic. Searching by subject headings (a.k.a. descriptors) is the most precise way to search article databases.
It is not easy to guess which subject headings are used in a given database. For example, the phone book's Yellow Pages use subject headings. If you look for "Movie Theatres" you will find nothing, as they are listed under the subject heading "Theatres - Movies."
Keyword searching is how you typically search web search engines. Think of important words or phrases and type them in to get results.
Here are some key points about each type of search:
- natural language words describing your topic - good to start with. How we talk/type.
- pre-defined "controlled vocabulary" words used to describe the content of each item (book, journal article) in a database
- more flexible to search by - can combine together in many ways
- less flexible to search by - need to know the exact controlled vocabulary term
- database looks for keywords anywhere in the record - not necessarily connected together
- database looks for subjects only in the subject heading or descriptor field, where the most relevant words appear
- may yield too many or too few results
- if too many results - also uses subheadings to focus on one aspect of the broader subject
- may yield many irrelevant results
- results usually very relevant to the topic
When you search a database and do not get the results you expect, Ask Us for advice.
What to look for
Records in library databases are comprised of fields containing specific pieces of bibliographic information. Common fields include:
- journal title
- date/year of publication
How database fields improve your search
- Limiting your search to specific database fields can yield more precise results.
- For instance, if you are looking for books by Adam Smith instead of about him, it is more efficient to limit your search to the author field.
- To find various fields within a database, look for drop down boxes or menus to select the field you want to search.
- Then combine words and fields together with boolean or proximity operators, depending on how precise you want to be.
- If you do not choose a specific field, the database usually reverts to a keyword search, where your words will be searched throughout the record.
- If your keyword search retrieves too many records (more than 50), try narrowing your search to retrieve a more manageable result.
- Information overload - too many results - can be a worse situation than finding only 10 very relevant results.
Need help understanding fields? Please Ask a Librarian.
Example of fields
The record belows shows the field names on the left: Author, Title, Source, Standard No., Details, Language, Abstract, Descriptor
What to look for
- Different databases interpret searches differently. A common variation is how databases recognize phrases.
- Some assume that words typed next to each other should be searched as phrases.
- Others automatically put a Boolean AND between your search terms, requiring that all the words be present, but not necessarily adjacent to each other.
- These searches can retrieve very different results.
Phrase searching tips
Most databases allow you to specify that adjacent words be searched as phrases.
- Using parentheses or quotes around search words is a common way to do phrase searching, but not all databases or search engines use them.
- Example: "genetic engineering"
What to look for
Stop words are frequently occurring, insignificant words that appear in a database record, article or web page.
Common stop words include:
About stop words
Why should you care about stop words?
- Many databases ignore common words from your search statement. If included, the database returns far too many results.
- So you know which words to exclude from your search statement.
- To make sure they are included if they are a significant part of your search.
- Many databases recognize common stop words when they are part of the controlled vocabulary of subject headings and descriptors. Example: balance of payments | theory of combustion
- Stop words vary by database. Check the Help screens for a list.
How can you avoid using stop words in your search?
- In some databases, you can use techniques to include stop words as part of the search.
- Some databases use quotes around stop words. Example: Title keyword= out "of" africa retrieves title: Out of Africa
Choose the most significant words that describe your topic and connect them together using Boolean operators or proximity operators.
Search for your terms in specific fields, such as author, title or subject/descriptor.