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INNER
The INNER attribute (PROP:INNER) specifies the JOIN structure declares an “inner join” instead of the default “left outer join.”
The VIEW structure defaults to a “left outer join,” where all records for the VIEW's primary file are retrieved whether the secondary file named in the JOIN structure contains any related records or not. Specifying the INNER attribute on the JOIN creates an “inner join” so that only those primary file records with related secondary file records are retrieved. Inner joins are normally more efficient than outer joins.
PROP:INNER is an array property of a VIEW indicating the presence or absence of the INNER attribute on a specific JOIN. Each array element returns one ('1') if the JOIN has the INNER attribute and blank () if it does not. The JOINs are numbered within the VIEW starting with 1 as they appear within the VIEW structure.
PROP:INNER is read-only for non-SQL views and read/write for SQL based views.
Example:
AView VIEW(BaseFile)
JOIN(ParentFile,'BaseFile.parentID = ParentFile.ID') !JOIN 1
JOIN(GrandParent.PrimaryKey, ParentFile.GrandParentID) !JOIN 2
END
END
JOIN(OtherParent.PrimaryKey,BaseFile.OtherParentID),INNER !JOIN 3
END
END
! AView{PROP:Inner,1} returns
! AView{PROP:Inner,2} returns
! AView{PROP:Inner,3} returns '1'
ViewOrder VIEW(Customer),ORDER('-Hea:OrderDate,Cus:Name')
PROJECT(Cus:AcctNumber,Cus:Name,Cus:Zip)
JOIN(Hea:AcctKey,Cus:AcctNumber),INNER !Inner Join on Header
PROJECT(Hea:OrderNumber,Hea:OrderDate) ! gets only custmers with orders
JOIN(Dtl:OrderKey,Hea:OrderNumber),INNER !Inner join on Detail file
PROJECT(Det:Item,Det:Quantity) ! is natural and more efficient
JOIN(Pro:ItemKey,Dtl:Item),INNER !Inner join on Product file
PROJECT(Pro:Description,Pro:Price) ! is natural and more efficient
END
END
END
END
See Also:
JOIN