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The LA Fox Developer Newsletter
February 1996
LOOKUP() (Con't from page 7)
seconds. This may not seem like a lot of time, but what if you put 20 lookup command calls on a report. Using the UDF would start to slow Foxpro down. Using the command wouldn’t.

Lookup() is a powerful command that can be used in screens, reports and even validation. To use as a validation command, just check for EMPTYO. If it’s not empty, the search key (or entered value) is valid, otherwise, the Lookup command will return an empty value and you can then indicate to the user that the entered value is was an invalid entry. Also, because the LookupO command returns the same data type as the requested field, you will never get a data type mismatch error when using this command.

Some final tips to remember when using LookupO:
1.
Always use fully qualified field names (alias.fieldname)
2.
Always use the fourth parameter (Tag Name)
3.
You can only return one field at a time using lookup, but you
can call Lookup multiple times.
4.
Lookup is fast... very fast.
5.
Lookup doesn’t depend on relationships being set.
[Michael Meer is Vice President of Microcomputer Engineering Services, LLC, a company that specializes in highly-customized FoxPro applications and mission- critical systems, and a certified Visual FoxPro trainer! instructor for MicroEndeavors, Inc.]

Simple Stuff (Con’t from page 6)
you would use CDOWO, DAYQ and CMONTHO
? CDOW({26106195}),str(DAY((26106195}),2)+’th’,;
CMONTH((26/06/95})

Note - The {} surrounding a date are the equivalent of the or” " delimiters which define character data. Separating the fields with commas leaves a space between each. Using ‘+‘ there are no spaces but data must be of Character type.

To list all transactions in a field called trans_dat in 1995 you would use the YEAR() function

list for YEAR(trans_dat) = 1995 [fields <field list>]

To list all bills still not paid three months after being sent out you would use the GOMONTHO function
list for dateQ> gomonth(trans_dat,3)

As with numeric fields, dates can’t be mixed as is’ with
character data if ‘+‘ is used to join fields.
? ‘Your letter dated ‘+ trans_dat

will generate the error

‘operator/operand type mismatch’.

The date needs to be a character string. Use -:

? ‘Your letter dated ‘+ dtoc(rec_on)

And for use in compound indexes you need the DTOSO function, which changes a date into a yyyymmdd string.
Index on cust_code + dtos(ord_date)
list field cust_code,ord_date

will produce a list ordered by customer with each customers’ orders listed in date order.

Well, that’s a start. I’ve avoided jargon as much as possible, and hope the level is what the originator of that thread thought was needed. Really the answer to which data type to use (when there is a choice) depends on how the data is to be used. You should use the data type that takes the least amount of coding to produce the required results.


Out and About (Con't from page 5)
search, go left by Laguna Canyon Road. They will meet in Building 1, in the back. Use the employee entrance. Since they have other business going on, do not arrive before 6:15 pm. For those making presentations, there will be a projection tablet available with 640 x 480 resolution only.

TechEd, sponsored by Microsoft, will be April 15-19, 1996, just in time to conflict with DB-Expo (in San Francisco). Cost of the event will be $1195, if registration is received by March 1, $1395 after. So start saving yaw pennies. For info, call 800/545-8240. The last notice I received stated that all information at the conference be delivered at an advanced or technical level.

LA Fox Board Meeting this month. Any current/paid up member of the group is welcome to attend. Details will be announced at the meeting.
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