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Initially the Query Tool shows three Groups to the users, but only one (the first one) is active. Users are to add criteria via drag-and-drop to the Groups to construct their queries. A number of potential i2b2 objects can be added to the Groups. They include ontology terms, previous queries, results of previous queries, and items from the Workplace.

    i. Adding i2b2 Objects into Groups

       1)

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Ontology Terms

The Navigate/Find Terms component contains all available ontologies. Users can browse or use its search functionalities to find a certain terms. After identifying the terms users wish to query for, they can drag and drop them into the Groups.

       2)

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Previous Query

The Previous Queries component lists all previously submitted queries. Users may drag and drop a previous query into a Group. When a new query contains a previous query is executed, i2b2 will run the previous query first. The previous query's results are then used in conjunction with the other terms in the new query to obtain the final results. In this sense, a previous query in a query can be thought of as a sub-query.

       3)

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Query Result (Patient Set/ Patient)

For each previous query in the Previous Queries component, its results such as individual patients or patient sets can also be dropped into the Groups.

       4) Including a Folder in Workplace

Workplace is a place where users can put any i2b2 objects such as ontology terms, previous queries, patient sets, etc. they wish to save for later. Users can then drag these saved objects into the query Groups. In addition,

    ii. AND/OR Operators

       Order of Precedents

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