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Conduct Your Search: sub-module 1 of 4 of start to search

Once you’ve chosen a search interface, it’s time to conduct your search. You may think that you don’t need to learn how to search a library database because you have experience using Google, but searching a library database is not the same as searching for information using Google. In this module, you will learn techniques for getting the best search results, including optimal keywords, Boolean operators, and subject headings. You can also see demonstrations of how to use common library databases for health sciences.



  • Use the right search language. Natural language searching works fine in Google, but not very well in databases. Keywords combined with Boolean operators and similar techniques are more effective in library databases.
  • Think of synonyms. When coming up with keywords for your search, consider incorporating synonyms and related terms.
  • Use Boolean Operators to include and exclude your search terms. Boolean Operators can tell the search interface if you want to search for both terms (AND), either term (OR), etc.
  • Use wildcards and truncation to find variations on words. Rather than searching for multiple variations of a word, you can use wildcards or truncation to search for several of them at once, e.g. nurs* to search for nurse, nurses, nursing.
  • Use subject headings for a more powerful search. Subject headings are the standard terms used to describe something. Once you know the subject headings for your topic, it will be easier to find the results you want.
  • When in doubt, check the help section for the search interface. The help section will explain how to use the database and use subject heading, as well as what symbols to use for wildcards and truncation.

How to Conduct a Search

About Search Language and Strategies

You may be used to searching in Google, but the wording you use to search a library database will need to be somewhat different. Here are the differences in search language between Google and a library database (or discovery layer):

  • In Google: You can type a question in the same way you might ask it in a conversation, for example: What are the health benefits of regular exercise? This is called searching using natural language.
  • In a library database:
    • Keywords: You should search using keywords, which are the words that hold the key idea of what you are trying to find. Learn more about Keywords.
    • Boolean Operators: You can combine or exclude your keywords in your search using words called Boolean Operators. Learn more about Boolean Operators.
    • Wildcards: You can search for words with spelling variations by replacing a letter with a wildcard symbol. Learn more about wildcards.
    • Truncation: You can search for variations of a word by adding a truncation symbol after the root of the word. Learn more about truncation.
    • Subject Headings: You can also use phrases called “subject headings,” which are the standard terms for specific topics, to help you find what you’re looking for. Learn more about subject headings.

Explore the tabs to learn more about the search language used in library databases.

How Do I Use Keywords?

The words you choose for your search will have an impact on the results you find. There are many different ways of describing the same topic. Doing the same search multiple times with a variety of terms will yield the most complete results.

Take a moment to learn more about Keywords, Synonyms and Related Terms.

Keywords are words that hold the essence, or the key idea, of what you are trying to find. Keywords are usually nouns, e.g. people, places or things. Don’t include words like why, what, where, when, if, the, etc. in your database search. Using relevant keywords in your search will lead you to better information. You can identify the first keywords from the topic itself. Try to think of 2 - 4 keywords. If you have too few, your search results won’t be specific enough, and if you have too many, you may get too few results.


  • Topic: Are text message reminders effective in maintaining lower blood sugars among teenagers with Type 1 diabetes?
  • Keywords: text message reminders, blood sugars, teenagers, Type 1 diabetes

Synonyms are words that have the same, or similar meaning as the main keywords. Synonyms of keywords are interchangeable, which means that the meaning of your search will remain the same. Synonyms can be used to broaden your search to retrieve more results.

Here are a few examples of synonyms for the topic: Are text reminders effective in maintaining lower blood sugars among teenagers with Type 1 diabetes?

  • Text message reminders: SMS reminders
  • Blood sugars: Blood glucose, glycaemia
  • teenagers: youth, high school-aged
  • Type 1 diabetes: juvenile diabetes

Related terms are words that generally mean the same thing as the main keywords. For example: tablet - device, car - vehicle, pop - carbonated drink. While related terms don’t mean exactly the same thing as the words they are replacing (synonyms), they are an excellent tool for broadening the scope of your search.

Here are a few related terms for the topic: Are text reminders effective in maintaining lower blood sugars among teenagers with Type 1 diabetes?

  • Text message reminders: email reminders
  • Blood sugars: hypoglycemia, hyperglycemia
  • teenagers: children, young adults
  • Type 1 diabetes: autoimmune disease

What Are Boolean Operators?

Boolean Operators, including AND, OR, and NOT, are words that make it easy for you to customize the results of your search. Watch the video and read the information below to learn more about Boolean Operators and how to use them.

When searching for information in a library database or a search engine, you may want to combine some keywords, or exclude certain words, to ensure that your search results are more focused or relevant to your topic.

TIP: In library databases, you don’t need to capitalize proper nouns (e.g. Twitter, Trudeau or Ontario), but Operators must be typed in all capital letters, e.g. NOT, AND, OR.

Using the AND operator tells the database that all words, or terms, that you have connected with AND must be found in any results returned.

If, for example, you are searching for articles about marketing with Twitter, you could search for: marketing AND Twitter. Only articles that include both Twitter and marketing will be in your search results.

The Operator NOT will narrow your search results by excluding or removing a specific word or words from the search results.

For example, if you’re researching marketing but are not interested in articles about marketing using Twitter, you could search for: marketing NOT Twitter.

Your results from this search will not include any articles that contain the word Twitter.

Be careful when using NOT, as it can remove results that would actually have been relevant. For example, if you were searching for articles about adolescents, adding NOT children to your search would remove all results that address both adolescents and children - and even articles with titles such as “Treatment X improves sleep in adolescents but not in children.”

For a broader search, to find articles that discuss marketing with Facebook or Twitter, you could use the Operator OR, e.g. marketing AND (Facebook OR Twitter). The results from this search will include articles that talk about marketing and Facebook, or marketing and Twitter, or marketing and Facebook and Twitter.

In the above example, you'll see that brackets are included in the search. When you are using more than one Operator in a search (e.g. AND and OR), you will need to group your keywords and operator words using brackets, so that the database knows which action to perform first.

How Do I Search for a Phrase?

Sometimes you might want to search for a phrase, where the words always appear together and in a specific order. Watch the video and read the information below to learn more about how to search for phrases.

When searching for an exact phrase, (i.e. exactly the same words in the same exact order), most library databases support the use of "quotation marks" (“ “) around the phrase, which could be two or more words.

Quotation marks instruct the database to return results that include that exact phrase. Searching for an exact phrase can help to reduce the number of irrelevant results.

For example, if you search for articles about body language (without quotation marks), your results will include both words, but body might be on the first page of the article, and language on the last.

Searching for “body language” will only return results that include that exact phrase. Using quotation marks to search for an exact phrase will narrow down your results and make them more relevant. Exact phrase searching with quotation marks will also work in Google.

There are, however, a few databases that do not recognize or support exact phrase searching using quotation marks. If you get no results, or too few, remove the quotation marks from around your phrase and search again.

What Are Wildcards?

A wildcard is a special character that replaces one or more letters in a word (e.g. colo#r) in order to search for multiple variations of the word. When keyword searching, you may miss relevant and useful results if the term you have searched for does not appear in that exact form in an article or book. Wildcard symbols can help you to find word variations so that you don’t miss anything.

To use a wildcard, insert the wildcard symbol used by that database to replace the letter that may change.

For example, if you do a search for pediatric and an article uses paediatric instead, that article won't be in your search results. If you searched using a wildcard, you could search for p#diatric and see results for both pediatric and paediatric.

Databases use different symbols for their wildcard. Common wildcard symbols used in different databases include:

  • the question mark (?)
  • the pound sign (#)
  • the dollar sign ($)
  • the percentage symbol (%)
  • the exclamation mark (!)

If you want or need to use a wildcard in your search, check the help section in the database you’re using to find the wildcard options.

What is Truncation?

To ‘truncate’ a word simply means to shorten it by removing one or more letters to go back to the root word. Truncating a word allows you to search for multiple variations of a word at once. You can do this by adding a truncation symbol (e.g. *) to the end of the root of the words. Like with wildcards, different databases use different symbols for truncation; check the database help to find out which one to use. Watch the video and read the information below to learn more about how to use truncation.

Let’s imagine we are searching for articles about the practice of nursing in Canada. If we search for those keywords only, nursing AND Canada, we may miss articles that include the words nurse, nurses, Canada’s or Canadians. If we truncate each word, we will get more results. So, to search nursing in Canada, we could truncate both keywords and search for: nurs* AND Canad*.

Tips for truncating:

  • Be careful not to truncate the word too much.
    Truncating too many letters from a word can lead to results that are unrelated to your intended search term. For example, searching for nursing in Canada using the truncated word nurs* will also bring back results about nurseries, and truncating Canada to Can* may retrieve articles with words like cantaloupe, cancer, canned, etc.
  • Google Scholar uses “automatic stemming”.
    This means it automatically treats your search terms as if they have a truncation symbol at the end, so a search for nurse would also return nurses, but not nursing.
  • Some databases have special rules around truncation.
    For example, you may or may not be able to use truncation inside a phrase (with quotation marks), and there may be a limit to the number of characters you must type before the truncation symbol (in PubMed, you must type at least 4 characters, so you would not be able to truncate nur*).

Database Help Pages

Databases typically have help pages and/or user guides to help you use that database. This is also where you can find information on wildcard and truncation symbols. See the information on the help pages for some common health sciences databases below.

In PubMed open in a new window, you can find the help page by clicking FAQ & User Guide, which will be located either under the search bar, in the section labelled “Learn.”

The homepage of the Pubmed database. The button for FAQs & User Guide is highlighted partway down the page, in the Learn category.

In CINAHL, you can find the help page by clicking Help, located in the top right of the page.

The homepage of the CINAHL database. The Help button is highlighted in the top right of the page.

In Google Scholar open in a new window, you can find the help page by clicking Help, located in the bottom right of the page.

The home page of Google Scholar. The Help button is highlighted in the menu at the bottom of the page.

Test Your Knowledge

How to Search in Databases using Subject Headings

Each database is different, and the process of searching is slightly different within each one. Many databases provide the option of searching using subject headings, which are designated terms for different topics. Knowing about subject headings and how to search in specific databases will make your search process easier. In the tabs, you can find information on the following topics:

  • What subject headings are and why you should use them
  • How to search with subject headings in CINAHL
  • How to search with subject headings in PubMed

Many databases provide the option of searching using subject headings. A subject heading is a word or phrase that is assigned to an article or other resource and describes the topic of the resource. It is a bit like a social media hashtag, but without the # symbol.

Subject headings use a controlled vocabulary, meaning that there is a list of possible headings that everyone who assigns them must agree upon. A single article might have multiple subject headings, especially if it covers a range of topics. Watch the video or read the information below to learn more about subject headings.

Searching by subject heading is more powerful than searching by natural language or even by keyword. When you search by keyword, that word might show up in a number of places in relation to the article, such as the abstract, the author’s name or the journal title, even if it’s not specifically what the article is about. This means your search results may include many articles that are not relevant to you. Conversely, when you search by subject heading, you are limiting your results to articles that are actually about that topic.

Not every concept has a subject heading, so in some cases you won’t be able to find a subject heading that means exactly what you’re looking for. Rather than trying to convert every keyword into a subject heading, it’s often best to use a combination of keywords and subject headings.

Subject headings are also useful because they are arranged in a hierarchy of broader and narrower terms, sometimes called a tree structure. Exploring the tree may give you ideas for search terms you hadn’t considered.

If you search Nurse-Patient Ratio as a subject heading and don’t find many results, you could look at the tree structure, find the broader term Personnel Staffing and Scheduling, and try that one instead. Here is what a portion of this tree looks like in CINAHL:

  • Health Services Administration
    • Management
    • Personnel Management
    • Personnel Staffing and Scheduling
      • Flexible Scheduling
      • Nurse-Patient Ratio
      • Personnel Staffing and Scheduling Information Systems
      • Shiftwork
      • Skill Mix
      • Understaffing
      • Work Assignments

Different databases use different subject heading systems, which means you will need to look up your subject headings in each database you use. Here are two common systems:

  • Medical Subject Headings (MeSH): This is one of the most common systems. It is used by PubMed, Medline, Cochrane Library, and others.
  • CINAHL Subject Headings: This is the system of subject headings used by CINAHL.

How to Search with CINAHL

Watch the video or read the instructions below to find out how to conduct a search in the CINAHL database. Visit your library website to access CINAHL.

To search in CINAHL:

  1. Once you have opened CINAHL, click Advanced Search.
  2. Make sure “Suggest Subject Terms” is checked, type in your search term (e.g. privacy) and click Search.
  3. Click on a relevant subject heading in the list, e.g. “Privacy and Confidentiality.”
  4. The tree view will appear; this view shows the broader and more specific terms for the subject. Select an additional term if it would be more appropriate for your search.
  5. Click the icon under the Scope column and read the Scope Note to make sure the subject heading means exactly what you think it means.
  6. Click the checkbox beside the term you want to use, e.g. “Privacy and Confidentiality”
  7. To the right of the Scope column, you’ll see a list of subheadings. If you see one or more that are particularly relevant to your search, you can select them now. Note: This will limit your search results. We suggest starting by leaving the “Include All Subheadings” box checked.
  8. Below the Search Database button, you can select either of the following two options:
    1. Explode: This option will give you more search results by including all narrower terms below your subject heading in the tree (in this example, Duty to Warn and Genetic Privacy).
    2. Major Concept: This option will give you fewer (but potentially more relevant) search results by limiting your search to articles where your subject heading has been flagged as a major concept, meaning it is especially important to the article.
  9. Click Search Database. You will see a list of results.

How to Conduct a Search using PubMed

Watch the video or read the instructions below to find out how to conduct a search in the PubMed database.

To search in PubMed:

  1. Open PubMed and click MeSH Database.
  2. Type your search terms into the search box and click Search. Your search results will show a list of MeSH headings related to your search term. Each comes with a brief definition to help you know which term you want to use.
  3. Select a MeSH heading from the list. This could be the same term that you originally searched, or you could see one that is a better option. This will display the MeSH record for that heading.
  4. Modify your search using any of the following options included in the MeSH record:
    1. Subheadings: Select any subheadings that would be relevant to your search. Be aware that this would limit your search results.
    2. Restrict to MeSH Major Topic: Check this box to see fewer (but potentially more relevant) search results by limiting your search to articles where your MeSH heading has been flagged as a major topic.
    3. Subject headings in the “tree view”: You can see broader and narrower terms related to your MeSH heading and select one of them if they would be more appropriate for your search.
  5. To run your search, in the “PubMed Search Builder” in the top right of the page, click Add to search builder. Your search term will appear in the box.
  6. Click Search PubMed to run the search. Your search results will show all the articles that have the term you chose as a major MeSH heading. Note: by default, in addition to the MeSH heading you’ve selected, PubMed also searches more specific terms beneath that heading in the tree structure.
  7. Refine your search as needed by adding additional terms, either as subject headings or as keywords. You can also try adding filters to your search; learn more about how to use filters in the module Filter Your Search Results.