why won't my Fetch.next fetch the next?

[Marion Wiffen]

I cannot find a programming error, but the following �snippet� refuses to co-operate.

Please tell me it is simple, just do this. . .



'Date Created: 30-Nov-2003 10:35:26 PM
'Last Updated: 06-Dec-2003 20:09:07 PM
'Created By :P.o.W
'Updated By :
debug(1)

'**************** start of record fetch ****

tbl = table.open("c:\asw work in progress\fox_dept\Booking Dates .dbf")

tbl.fetch_first()

WHILE .NOT. tbl.fetch_EOF()

IF booking dates->Datesfixdate then tbl.fetch_next()

end if

�**************** start of data entry ******



fixdate is a global variable that contains 01/05/2004 from a different table.

Booking dates->dates is a �calender� field (365 records) first record =01/01/2004

I have tested this in debug, and the variable and field do contain the desired data.

The fetch loop should tbl.fetch_next (five records) until �dates� field = fixdate variable.

It never loops. The line:

IF booking dates->Datesfixdate then tbl.fetch_next()

does nothing. no other records are fetched, the date is not incremented, and subsequently data is entered into the wrong records

If anybody can see a syntax error, or suggest a more foolproof way of doing this, I would be very pleased.

I have spent many many hours on this xbasic section, and at last it is beginning to work, thanks also to the �forum folk�. This is probably the the last piece of the puzzle I need.

When it finally works I intend to post it, in the hope that it may be of use to someone else as well.


Marion

[Stan Mathews]

RE: why won't my Fetch.next fetch the next?

Unless there's a cut and paste error

IF booking dates->Datesfixdate then tbl.fetch_next()

end if

should be

IF booking dates->Datesfixdate then

tbl.fetch_next()

end if

and the "then" is not really necessary.

IF ... THEN ... ELSE

Syntax

IF Logical_Expression1 [ THEN ] "---"then" optional
[ Statements1 ] "---program statements on next line
[ ELSEIF Logical_Expression2 [ THEN ]
[Statements2]]
...
[ ELSEIF Logical_ExpressionN [ THEN ]
[ StatementsN ]]
[ ELSE
[ Statements ]]
END IF

[PhilD]

RE: why won't my Fetch.next fetch the next?

Theres also a space in the path that shouldn't be there unless it is a typo.
tbl = table.open("c:\asw work in progress\fox_dept\Booking Dates .dbf")

Should be:
tbl = table.open("c:\asw work in progress\fox_dept\Booking Dates.dbf") (no space between dates and .dbf)

Phil

[Marion Wiffen]

RE: why won't my Fetch.next fetch the next?



tbl = table.open("c:\asw work in progress\fox_dept\Booking Dates .dbf")

tbl.fetch_first()

WHILE .NOT. tbl.fetch_EOF()

IF booking dates->Dates=fixdate (I changed it from

tbl.fetch_next()

end if


Stan, (and Phil)

Thanks for the replies, (been away for few days).
I made the changes and had some success.

Although the fields of the calender table NEVER get filled in when the application is actually running, It does work about one in ten times, when run in debug mode.

When it fails, record one is fetched OK, but then the pointer just switches back and forth between -

IF booking dates->Dates=fixdate

and

tbl.fetch_next()

It never actually fetches the next record and "dates" does not increment. stays at 01/01/200x

I have added a counter to close the table if it gets into a "failed fetch loop", but when I run debug again it is more likely to fail than to work, so closing the table doesn't seem to help.

I appreciate this is getting more difficult to explain, and a little frustrating.

I have compared the syntax to various examples in the manuals, and it all looks correct.

Any thoughts on perhaps using some sort of "reset" to set the pointers to zero or something? I cannot figure out why it is so intermitant.

Marion

[Tom Cone Jr]

RE: why won't my Fetch.next fetch the next?

Marion,

There's no substitute for showing the entire script. Even better, post a working model of the database for us to see.

In the script snippet you've posted the fetch_next statement only fires if the IF condition is true. Is this what you need? How will the script ever advance through all the records once it hits a false IF condition?

I'd consider rearranging the sequence like this:

- open the table
- fetch the first
- begin the while loop setting eof condition as terminus

--- if condition 1 is true then
------ processing here 
------ processing here
--- end if

- fetch the next record

- end the while loop

This puts the fetch next statement inside the while loop where it belongs, but outside the IF block so that all records are checked for the IF condition.

-- tom

[Tom Cone Jr]

RE: why won't my Fetch.next fetch the next?

Marion,

There's no substitute for showing the entire script. Even better, post a working model of the database for us to see.

In the script snippet you've posted the fetch_next statement only fires if the IF condition is true. Is this what you need? How will the script ever advance through all the records once it hits a false IF condition?

I'd consider rearranging the sequence like this:

- open the table
- fetch the first
- begin the while loop setting eof condition as terminus

--- if condition 1 is true then
------ processing here 
------ processing here
--- end if

- fetch the next record

- end the while loop

This puts the fetch next statement inside the while
loop where it belongs, but outside the IF block
so that all records are checked for the IF condition.

-- tom

[Stan Mathews]

RE: why won't my Fetch.next fetch the next?

What Tom said...

so what you probably want is something like

tbl = table.open("c:\asw work in progress\fox_dept\Booking Dates .dbf")
tbl.fetch_first()
WHILE .NOT. tbl.fetch_EOF()
IF booking dates->Dates=fixdate
'some command here to change the booking dates->Dates
end if
tbl.fetch_next()
end while
tbl.close()

Which leads to some other points...

you have to put the table in change mode prior to changing any of the field values.

IF booking dates->Dates=fixdate
tbl.change_begin()
'some command here to change the booking dates->Dates
tbl.change_end(.t.)
end if

and while we're using pointer methods
IF booking dates->Dates=fixdate
should be
IF tbl.Dates=fixdate

And in an unrelated matter, table names should not contain spaces so

booking dates
should be
booking_dates

or similar.

[Marion Wiffen]

RE: why won't my Fetch.next fetch the next?

All taken on board with thanks,

The whole idea is to fetch records until the correct appointment date is reached, at that stage a GOTO comes in and drops the pointer down to a tbl.change_begin() and series of CASE queries.

The problem is that the correct date is not fetched, so the CASE is never tested, and the fields not filled.

I will post the table, and it will explain all, (plus my somewhat basic prog skills), still, whats a little embarrasment if it leads to a solution.

Thanks all,
I will return.

MDW

[Marion Wiffen]

RE: why won't my Fetch.next fetch the next?

Stan, Phil, Tom,

Seems you have cracked it for me.

I ran through the layout and syntax(es) you had suggested/pointed out, and what seems to have unblocked the drain is TBL.DATES as opposed to the longhand i was using.

I had not come across tbl.field in the manuals. What a learning curve it can be.

I would have trouble telling you guys just how grateful I am. in case no other insurmountable problems crop up this year, Have the best Christmas ever, and don't worry, there will be further challenges ahead I'm sure.


MDW