Yes, single valued and Pick. This works for me. Thanks all.
Schalk
On Thu, 11 Mar 2004 08:30:02 -0500, Stevenson, Charles <[EMAIL PROTECTED]> wrote:
> Can somebody help me with the syntax of EVAL. I want to execute a > SELECT on a file to get all records where (field 16)*0.9 < field(17).
Various ways to do this. Try... SELECT file WITH EVAL "F16 * 0.9 < F17" = 1 where F16 and F17 are field names from the dictionary.
The most common mistake is to miss off the = 1 at the end. Remember, this EVAL expression is going to return true or false.
1. Yes, but put quotes around the final literal 1:
WITH EVAL "F16 * 0.9 < F17" = "1"
or it will try to find a record called "1" in both the dictionary and VOC. Many Pick-style dicts have that. Even if it doesn't exist today, it might in the future.
2. You might be tempted to do:
WITH EVAL "F16 * 0.9" < F17 (or WHEN '' '' '' '' for multivalued data)
which will probably work, but with EVALs you sometimes need to include explicit formatting & conversion on the command line. RetrieVe sometimes outsmarts itself when sorting BY an EVAL or using an EVAL as a display column. By default it sometimes assigns to the EVAL the conversion & justification of an element inside the EVAL. Annoying, that. All this makes Martin's answer better, since it is more explicit.
3. If you use Pick-style dictionaries, you can still use EVALs, and you can extract the fields you want:
WITH EVAL "@RECORD<16> * 0.9 < @RECORD<17>" = "1"
4. All this assumes single-valued fields, right? Let us know, because if either F16 or F17 are multi-valued, you'll need a variation on the theme by using "LTS" function and/or the WHEN keyword.
Chas. Stevenson
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