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From: bmug@garnet.berkeley.edu (BMUG)
Newsgroups: comp.sys.mac
Subject: Re: 4D 2.0 question
Message-ID: <1989Oct3.145614.24672@agate.berkeley.edu>
Date: 3 Oct 89 14:56:14 GMT
References: <35206@apple.Apple.COM>
Sender: usenet@agate.berkeley.edu (USENET Administrator;;;;ZU44)
Reply-To: bmug@garnet.berkeley.edu (BMUG)
Organization: University of California, Berkeley
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In article <35206@apple.Apple.COM> chuq@Apple.COM (Chuq Von Rospach) writes:
>Here's a question for the folks who are using 4D. I've got a file with a
>unique key. I'm going to be generating that key in a procedure, and I want
>to check for the previous existence of that key programmatically. What is
>the most efficient way of doing that?
>

The way I'd do it would be to enter the key into a variable, do a PUSH
RECORD, search for the key (should take a few milliseconds if the key
field is indexed), do a POP RECORD if the search comes up empty (and
continue entering your record), or bring up an appropriate alert or
dialog if the key already exists, and give the user the opportunity
to enter a new key (then search, etc.) before POPping the RECORD.

4D will automatically catch an attempted entry into a unique field
where a key already exists, but if you'll be generating field contents
procedurally, this will give the user some added control, with an
extremely small sacrifice in speed.

John Heckendorn
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