You use the CROSS clause to perform the following tasks:

       o  Compare records from one domain or collection

       o  Combine records from two or more domains or collections

       o  Flatten hierarchical domains to ease access to the list items

       Format

         CROSS  [context-variable IN]  rse-source

                [OVER field-name]  [...]

1  –  Arguments

    context-variable

       Is the name of a valid context variable. A context variable is a
       temporary name that identifies a record stream to DEC DATATRIEVE.

    rse-source

       Is the record selection expression (RSE) that identifies the
       records you want to work with.

    field-name

       Is a field whose values form the basis for the cross operation.

2  –  Example

       The following query uses one RSE that includes five out of the
       six optional elements of an RSE. DEC DATATRIEVE processes the
       query far faster than if nested FOR loops were used:

       DTR> DEFINE PROCEDURE CROS
       DFN> READY YACHTS
       DFN> PRINT BUILDER, RIG, A.RIG OF
       DFN>   A IN YACHTS CROSS YACHTS OVER BUILDER WITH
       DFN>   RIG GT A.RIG REDUCED TO BUILDER, RIG, A.RIG
       DFN> END_PROCEDURE

       DTR> :CROS

       MANUFACTURER  RIG    RIG

        AMERICAN    SLOOP  MS
        CHALLENGER  SLOOP  KETCH
        GRAMPIAN    SLOOP  KETCH
        IRWIN       SLOOP  KETCH
        ISLANDER    SLOOP  KETCH
        NORTHERN    SLOOP  KETCH
        PEARSON     SLOOP  KETCH

       DTR>