Re: Üsing Logicals?

Hi, Tim

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 a. & b. 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 55401-2499
(612) 371-1111 x480


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