Re: Join Logical on Physical files?

On 23 May 2013 15:29, Crystal Reports wrote:

I have several logical files that I wanted to create one Join Logical
file but I see that you can only do the join on Physical files.

Replace each DDS LF with an SQL VIEW, and then create a VIEW that joins those VIEWs in its SELECT; i.e. while a DDS LF can not be created over a DDS LF, an SQL VIEW can be created over an SQL VIEW.

Now if I join on Physicals, how can I keep the keyed order that I
have with the existing logicals?

A DDS JLF will allow keys from the /primary/ file in the join.

As I would lose the performance and process benefits of the keys.
<<SNIP>>

The JFLD in the secondary file have keys implicitly created during the ADDLFM [which is implied work on CRTLF MBR(other_than_*none)] to implement the join at open\run-time. In effect, the open of a JLF is little different than a query, except that its keys are decided at create-time and can not be optimized to choose something better or more appropriate at run-time.

A VIEW is not keyed, so only a query of the VIEW [which could be via OPNQRYF] which includes the sort specification will enable ordering.

Specific examples probably would be clearer than /words/ trying to describe what is a concern; i.e. for words without the supporting DDL or DDS and for performance concerns, also the cardinality of the data.