XBASIC - DELETING CHILD RECORDS

[Jenny Lynch]

As a newcomer to xbasic - I am puzzled by the following:

I have a Docket Header (parent table) with Docket Lines as child records. I have a DELETE button on a form, and I wish to delete all child records first before I delete the header.

Example Docket Header has 3 child records A, B & C

Can anyone please tell me why the following code displays and deletes the 1st & 3rd and leaves the 2nd one there ?
-------------------------------------------------------
dim mesg as c
dim t1 as p
dim t2 as p
dim qty as n
t1=table.current()
t2=table.get("Docket Lines")
t2.fetch_first()
while .NOT. t2.fetch_eof()
if t1.number = t2.number then
qty=t2.Qty
mesg=t2.stockcode+qty
ui_msg_box("",mesg)
t2.change_begin()
t2.delete()
t2.change_end(.T.)
end if
t2.fetch_next()
end while
-----------------------------------------------------

yet if I take out the lines

t2.change_begin()
t2.delete()
t2.change_end(.T.)

all 3 records are correctly displayed in the message box.

Am I not understanding how the delete works? It looks straight forward to me.

Any help would be greatly appreciated.

Many thanks
Jenny

[Stan Mathews]

RE: XBASIC - DELETING CHILD RECORDS

If iI remember correctly,

t2.delete() performs a fetch_next() as part of its process. Therefore your own .fetch_next() skips over the second child record.

[Jenny Lynch]

RE: XBASIC - DELETING CHILD RECORDS

Thanks Stan - but why does it only do that on the 2nd record? For example, I have tested 10 child records, and all are deleted except for the 2nd. Do you have any suggestions that may make this code work?

regards
Jenny

[Tom Cone Jr]

RE: XBASIC - DELETING CHILD RECORDS

Check the docs explaining the delete method you're using. If the record pointer is being moved by Alpha Five itself, your fetch_next() moves it again. -- t

[Jenny Lynch]

RE: XBASIC - DELETING CHILD RECORDS

Hi Stan

I have now changed the code to:

dim mesg as c
dim t1 as p
dim t2 as p
dim qty as n
t1=table.current()
t2=table.get("Docket Lines")
t2.fetch_first()
while .NOT. t2.fetch_eof()
if t1.number = t2.number then
qty=t2.Qty
mesg=t2.stockcode+qty
ui_msg_box("",mesg)
t2.change_begin()
t2.delete()
t2.change_end(.T.)
else //***** changed
t2.fetch_next()
end if //***** changed
end while


and this now appears to work ok, i.e. the fetch_next is NOT performed when the delete is done.

Thanks for the help.

regards
Jenny

[Jenny Lynch]

RE: XBASIC - DELETING CHILD RECORDS

thanks Tom also

[G Gabriel]

RE: XBASIC - DELETING CHILD RECORDS

Jerry:
In your set structure, did you choose cascade changes/delete?
Gabe

[Jenny Lynch]

RE: XBASIC - DELETING CHILD RECORDS

Gabe

No I haven't played with Referential Integrity yet. Will try that method as well.

thanks
Jenny

[G Gabriel]

RE: XBASIC - DELETING CHILD RECORDS

Jerry:
You wrote: " I wish to delete all child records first before I delete the header. "
I am not quite sure what you are trying to do:
1-Are you trying to delete the child records then delete the parent record at the same time but in that sequence? or
2-Are you trying to delete the child records and preserve the parent record to delete in a later date?
Based on what you are trying to do, there could be VERY SIMPLE ways to do that without any need for any xbasic.
Please clarify.
Thank you
Gabe

[Jenny Lynch]

RE: XBASIC - DELETING CHILD RECORDS

Gabe

As I said initially, I am quite new at A5 so at this stage I am just playing with xbasic code to see how things work. I have just tried the Referential Integrity method with cascade changes/delete as you suggested - which excludes the need for xbasic code. That works fine when I want to delete parent and all child records.

I have the xbasic code working fine now too, so thanks everyone for your help.

regards
Jenny