access columns via index

[MrDontKnowNothing]

hello everybody,

i'd like to scan a table. but instead of using the column-names to access the fields, i'd rather want to use indices, just like acessing an array.
but i don't want to copy the table into a array.

i appreciate any ideas...

cheers

alex

 

[craigsboyd]

I'm not sure exactly what you mean, but you can use KEY() and TAG() to figure out stuff about the indexes of the currently selected table, if your meaning was to do this kind of dynamically. Could you explain a little more about what you are trying to do, or give some psuedo-code?

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[sub]craig1442@mchsi.com[/sub][sup]

"Whom computers would destroy, they must first drive mad." - Anon​

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[MrDontKnowNothing]

sorry! actually i do have 2 problems...

1.)
usually, you acces a field via name e.g.:
select name, street from friends

but asume, that "name" is the 1st column and "street" is the 3rd column. now, i wanna do something like this:
select friends(1).value, friends(3).value from friends

2.)
when importing an excelfile, how can i make the first row to field-names?

muchas gracias

alex

 

[Mike Lewis]

Hi Alex,

I'm not sure what you mean, but I'd guess you need the FCOUNT() and FIELDS() function. For example:

FOR lnI = 1 TO FCOUNT()
lcField = FIELDS(lnI)
? &lcField
? TYPE(lcField)
ENDFOR

Is that what you had in mind?

Mike


Mike Lewis
Edinburgh, Scotland

http://www.ml-consult.demon.co.uk

 

[MrDontKnowNothing]

not as nice as i want it, but it will work.

it seems, that in vp7 accesing fields is done usually over the names, doesn't it?

anyway, thanks a lot for your help!

cheers

alex

 

[craigsboyd]

MrDontKnowNothing,

In addition to what Mike said, check out the AFIELDS()

Slighthaze = NULL
[sub]craig1442@mchsi.com[/sub][sup]

"Whom computers would destroy, they must first drive mad." - Anon​

[/sup]

 

[ramani]

HI

You have not phrased the question properly.

but asume, that "name" is the 1st column and "street" is the 3rd column. now, i wanna do something like this:
select friends(1).value, friends(3).value from friends

There has to be column2 with something and may be you have not said about that.

You can always get as given below..

USE myTable

aa = FIELD(1)
bb = FIELD(3)

SELECT &aa, &bb FROM DATA\myTable


SELECT EVAL(FIELD(1)), EVAL(Field(2)) FROM ...
will work, but the field size truncations will take place based on the first record selected.





____________________________________________
ramani - (Subramanian.G)

http://winnersoft.coolfreepages.com/

When you ask VFP questions, please add VFP version.

 

[MrDontKnowNothing]

well, the afields() would be approbriate, but i don't think it would be a good idea to put a lot of data into a array... (eats up memory, doesn't it?)

ramanis version is, what i actually wanted, but is there a way to do it inline? i have tried:

scan
if &field(1) = "" then
wait window 'hello'
endif
endscan

but it didn't work at all. i got the message: missing operand

gracias

alex

 

[Mike Lewis]

Alex,

but i don't think it would be a good idea to put a lot of data into a array... (eats up memory, doesn't it?)

With Ramani's suggestion, you are not putting data into the array. The array is just holding the names of the fields.

Mike


Mike Lewis
Edinburgh, Scotland

http://www.ml-consult.demon.co.uk

 

[MrDontKnowNothing]

sorry, this was corresponding to the suggestion with AFIELDS().

probably gonna start my weekend and check out things on monday ;-)

cheers alex

 

[Mike Lewis]

Alex,

Another thing to keep in mind: If you rely on field numbers rather than field names, you could run into problems if you ever change the structure of the table. In general, the order of the fields within the structure is not significant. By relying on the field numbers, you are introducing a dependency that would not otherwise be there.

Mike


Mike Lewis
Edinburgh, Scotland

http://www.ml-consult.demon.co.uk