There are several ways to prevent duplicate information in query results. For example, when you first create the query, use the correct source view. For information about source views, refer to Source Views.
To eliminate as many duplicates in query results as possible, follow these recommendations.
Limit the number of output fields in the query. Specifically, limit the number of one-to-many fields such as Transaction type or Phone number. For example, if you include Phone number in the output, and a constituent has multiple phone numbers, each number appears on a separate row in the query results. However, when you save the query and use it to generate labels, the constituent’s name appears only once.
Create a selection for each filter. For example, to create an ad-hoc query that returns all constituents with a cell phone and a home address in South Carolina, create a query to identify all the constituents with Phone type equal to "Cell" and create a selection from the results. Next, create a query to identify all the constituents with an Address type equal to "Home" and State equal to "SC" and create a selection from those results. To create the final query, add the two selections to the filter criteria and specify the records must exist in both selections.
Increase the number of filters in the query. For example, when you filter Number, also filter Phone type to limit the phone number to a specific type.
For a query that does not contain one-to-many fields, configure the query’s properties to suppress duplicate rows.
Note: Use the suppress duplicate rows option when you use fields from more than one query node to filter data, but do not use the fields from the additional nodes in the output. For example, if you include fields from the Addresses node to create a selection of constituents in a certain state, but do not include the address fields in the output, then constituents with more than one address in the state could appear in the results multiple times.
Include the system record ID field under Result fields to display and use the COUNT function from the Summarize button. For more information about how to use the Summarize button to suppress duplicates, refer to Summarize Query Output