Re: Derived Index V6R1

On 30-Aug-2011 06:25 , Schutte, Michael D wrote:

Looking for a best solution for implementing and using derived index.
I have a table that has a date in it MMDDYYYY format. It's a large
historical file that we often fight with getting data from. I would
like to create this derived index with the date as YYYYMMDD...

create index mylib/r06_derived on mylib/sales
( company
, dec(substr(digits(dcodte),5,4) concat
substr(digits(dcodte),3,2) concat
substr(digits(dcodte),1,2), 8, 0) as dtyyymmdd
)

Not sure why the additional DEC casting would be desirable, since
that just makes the expression even more verbose.?

This creates just fine. My question is how to use it.

Personally I would hate to duplicate "company = ? and
dec(substr(digits(dcodte),5,4) concat
substr(digits(dcodte),3,2) concat
substr(digits(dcodte),1,2), 8, 0) between ? and ?"
in every SQL statement I write to use the derived index.

I could create a view over the physical file that does cast dcodte
to the format I want, then I can select from the view using the new
field. Ideally, I would be able to use a UDF (not supported).

The following expression(s) might be more succinct [¿and functional?]
alternatives. And the two expressions will have the benefit [or
difficulty] of requiring a date\time[stamp] data type for the predicate
instead of the decimal data type used in the quoted example:

TIMESTAMP_FORMAT(DIGITS(dcodte), 'MMDDYYYY')

DATE( TIMESTAMP_FORMAT(DIGITS(dcodte), 'MMDDYYYY') )

<<SNIP UDT ref\question>>

Regards, Chuck
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