QueryDef Object

A QueryDef object defines the parameters for a query, which is used to retrieve specific records from a database.

A QueryDef object contains a query expression and a list of display fields. The query expression defines the search parameters for the query and can contain a complex set of conditional statements. To run the query, you must create a ResultSet Object and call its Execute method. (You can use the Session object BuildResultSet method to create the ResultSet object.) The ResultSet object uses the list of display fields in the QueryDef object to summarize the search results.

To create a QueryDef object,

  1. Call the Session object's BuildQuery method. The BuildQuery methods returns an QueryDef object with display fields and filters undefined.
  2. Add the filters and fields for your query to the QueryDef object.

To create a query that will return all records of a given type, create a QueryDef object, but do not add filters to it. Instead, add the fields to be returned using the QueryDef object's BuildField method.

You can add filters and nodes to a QueryDef object to create more complex queries. The nodes of a QueryDef object consist of one or more QueryFilterNode Objects, each containing one or more filters. Nodes group together each of their filters under a single boolean operator. You use the QueryDef object's BuildFilterOperator method to create the root node in this tree. After that, you use the methods of QueryFilterNode to define the remaining nodes and filters. The filters themselves can use other comparison operators to test the relationship of a field to the specified data.

For example, in the following statement:

Select * from <some defect> where (....) AND1 ((...) OR2 ( (...) AND3( (...) OR4 (...))))

the root operator is AND (AND1). Its next level sub-node operator is an OR (OR2). The complete hierarchy is:


   AND1 (AND1 is the root operator)
   \
      OR2 (OR2 is suboperator of AND1)
       \
         AND3 (AND3 is suboperator of OR2)
         \
            OR4 (OR4 is suboperator of AND3)
Note: You can also construct a query from a raw SQL query string using the Session object's BuildSQLQuery method. However, this technique does not create a QueryDef object.

For an example of how to use QueryDef object, see Running a query that has dynamic filters.