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The LA Fox Developer Newsletter
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September 1995
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Error Trapping
(Con't from page 3)
Hot Tip
.
At one time or another, almost everyone needs to do a lookup on address. The requirement I had was to aHowthe userto name a street, streettype like DR, LN,
PKVVY,
HWY, etc., street direction like E,W, N, S, as well as the house number to get to a browse screen. The user may want the browse to include all streets whose name begins with “CANNON” and whose street
type
is "BLVD", so that all properties for CANNON BLVD, CANNON TEMPLE BLVD, etc. would populate the browse window.
My solution was to use
code
like
My assumption is that the street name is the item which is most likely to be known. When running the program however, bad response became an issue. If I entered “CANNON” as the street name with everything else empty, response was fast. If I add I character to ANY other field, things got slower. Two
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characters
made
it
slower still.
In trying to debug the problem I created a small function which always returned TRUE, but added one to a local variable. I put this function in the BROWSE FOR clause so that after the browse was through, I could see how many records were beEng compared in the FOR clause of the browse. Sure enough, the more characters entered in houseno, for instance, the more records were being compared in the FOR clause, until a full Table search was being performed. I knew that there were 100 records with a street name of “CANNON”, but all I million records were being searched. This is not what I
ex
pected at all, but fortunately the solution is very simple.
PUT THE KEY CLAUSE IN FRONT OF THE FOR CLAUSE, and life will be good again. Imagine that!!!.... I
could
not find any documentation which suggests the order of the clauses wou’d make any difference, but it surely does. The good code looks like
Boy, is this fast!!!! I hope this tip might save you several days of debugging time! This problem exists in FPW 2.5b and FPW 2.6 and FPW 2.6a.
We’ve come up with an easy way to submit articles to the
LA
Fox
Developer Newsletter
one that has been overlooked for a long time.
You
can
submit your articles to either Chuck Williams
(72330,2326) or Barry Lee (72723,3422) on
Compuserve.
These articles
can
be on any FoxPro-related topic, whether it concerns a new technique you’ve discovered, a certain development technique you may favor over others, book reviews, etc.
The quality of this newsletter really depends on the members that support it, not just read it. And I think we’d all be surprised by the useful information that could be circulated around the membership.
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