AND/OR

Located to the right of the search bar are two radio buttons for the search operators AND and OR. By default, the iSearch COVID-19 Portfolio uses the AND search operator between all search terms and phrases. AND requires all terms and phrases to occur in each record returned. Records that mention one of the search terms or phrases but not the other(s) will be excluded from the results.

Conversely, OR will return results where one, some, or all of the search terms or phrases occur in each record. Use the OR operator when it is not necessary for all terms or phrases to occur in each of the resulting records.

Some fields, like PMIDs, are unique to each record. When using of list of unique identifiers in a search be sure to switch the search operator to OR to return the appropriate results. If you execute a query and return zero results, check your query syntax and search operator and review the Advanced Search section for query syntax rules and suggestions.

When you use a boolean operator (AND or OR) within your query syntax, the boolean operator in the query overrides the selected search operator to the right of the search bar. For example, if your query contains an OR boolean operator between the search terms or phrases and the AND operator is selected to the right of the toolbar, the OR the in the query syntax is the operator used to conduct the search.

If you switch the search operator used to conduct your search after your initial search be sure to click the Search button to rerun the search with the newly selected search operator.