Buck (et al.),

Here's a expurgated, non-Eudora version of an earlier submission. BTW, I fixed an error in the first message, in step d. below.

At 10:18 AM 11/2/97 -0500, you wrote:
>Good day to all;
>I am wondering about using logical files; say I have a logical built
>over a large file and we need another logical which is very close to the
>structure of the already logical file, with the exception of one field
>and the logicals key sequence. Is there another way to manipulate the
>existing logical (without having to build another logical)?
>I appreciate all responses

There are different possibilities, IMO.

1. 2nd logical's key is shorter than 1st logical's, with no skipped
fields in the key.

E.g., key1=fld1,fld2,fld3
key2=fld1,fld2

In this case, a single logical can suffice, if there are no
select/omit needs or data field restriction needs.

2. 2nd logical's key is shorter than 1st logical's, with skipped
fields in the key.

E.g., key1=fld1,fld2,fld3
key2=fld1, fld3

In this case, you can navigate the 1st logical as if using
the 2nd key. It involves something like the following process:

a. Using fld1, SETLL into the logical and then READ
(not READE).
b. Using fld1, the value you retrieved for fld2, & fld3,
CHAIN into the logical. If found, process it.
c. Using fld1 & fld2, SETGT into the logical and then READ.
d. Repeat steps b. & c. until EOF.

Or something like that.

BTW, most of the logicals we use are different only by key. We have some where we have a different field list, but not too many. We also have some with select/omit and calculated fields, but, again, not too many. FYI

HTH


Vernon Hamberg
Systems Software Programmer
Old Republic National Title Insurance Company
400 Second Avenue South
Minneapolis, MN 55401
(612) 371-1111 x480


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