Query syntax can refine your search. A query consists of terms and operators: terms are words or phrases; operators are simple words (AND, OR, NOT) used as conjunctions to combine or exclude search terms. Placing the search terms in quotation marks will further refine the results.

Terms
There are two types of terms: Single Terms and Phrases.

• A Single Term is a single word such as surgery.
• A Phrase is a group of words, e.g., ambulatory surgery or knee replacement.
• Multiple terms and phrases can be combined with Boolean operators (AND, OR, NOT) to form complex queries.

Using Quotation Marks
Using double quotes ("insert term here") around a phrase will match only the pages where the terms appear in the exact order in which the terms appear within the quotes.
E.g., while knee replacement returns all pages containing both replacement and knee in either order anywhere in the page, if you want the phrase "knee replacement" only in that order, use the search: "knee replacement"

Boolean Operators
Boolean operators (AND, OR, NOT) allow terms to be logically combined or excluded. Boolean operators are written in upper case.

• AND
  The HCUP-US search uses the AND operator as the default conjunction operator. This means that if there is no Boolean operator between two terms, the AND operator is used. E.g., searching for knee replacement returns identical results to searching for knee AND replacement.
  The AND operator matches documents where the terms exist anywhere in the text of the page or document, not necessarily in the order you typed. E.g., A search for knee replacement returns all pages that contain both terms in either order, including a document describing "hip replacement or knee arthroplasty."
  If you want the phrase "knee replacement" only in that order, place it in double quotes: "knee replacement"


• OR
  The OR operator links two terms and finds a matching page or document if either of the terms exist.
  For example, to search for documents that contain either "hip replacement" or "knee replacement" use the query: "knee replacement" OR "hip replacement"


• NOT
  The NOT operator excludes documents that contain the term or phrase after NOT.
  To search for documents that contain "knee replacement" but not "arthroplasty" use the query: "knee replacement" NOT arthroplasty
  To search for documents that contain "knee replacement" but not "hip replacement" use the query: "knee replacement" NOT "hip replacement"