How to Copy values of current record

[John Panagia]

I'm writing a script that processes all records in a table. I need to hold the values of the previous record read for summarizing purposes. Is there a way to copy the values of the current record to a Dot varaible? I need to compare values of the current record to the prior records values.

Thanks
John Panagai

[Jim Chapman]

RE: How to Copy values of current record

Hello John,

>>I need to hold the values of the previous record read for summarizing purposes....I need to compare values of the current record to the prior records values.

[John Panagia]

RE: How to Copy values of current record

Thanks Jim,

I am already doing it the way you describe. I was hoping there was a command like the Foxpro Scatter/Gather commands. I need to work with more than a few fields and it would be convenient to do it in a single command.

John

[Robert Adler]

RE: How to Copy values of current record

John:

Look at the .record_data_get([Record]) command.

I hope this helps.

bob adler

[John Panagia]

RE: How to Copy values of current record

Hi Robert,

I looked at the record_data_get method, it returns the record as raw data as a blob. It Does not give access to individual fields.

Thanks

[Peter.Wayne]

RE: How to Copy values of current record

you can create a property array with one element and use the .initialize_from_table() method.

[John Panagia]

RE: How to Copy values of current record

Hi Peter,

How would I load it with the current record within a fetch loop?

Thanks

[Stan Mathews]

RE: How to Copy values of current record

Borrowed heavily from the documentation, creates a variable for every field in the current table and assigns the current records' value.

FUNCTION Scatter AS L ()
scatter = .F.
tbl = table.current()
FOR i = 1 TO tbl.fields_get()
fld = tbl.field_get(i)
evaluate_template("dim global " +fld.name_get() + " as "+ fld.type_get())
eval(fld.name_get()) = fld.value_get()
NEXT I
scatter = .T.
END FUNCTION

[John Panagia]

RE: How to Copy values of current record

Thanks Stan,

Just what I was looking for. Maybe Alpha will implement scatter/gather commands in a future release.

John

[Stan Mathews]

RE: How to Copy values of current record

Do you want a gather() function as well? I haven't examined the possibility but it should be doable.

[Peter.Wayne]

RE: How to Copy values of current record

well, this is somewhat off the top of my head, so i may have the syntax slightly wrong.
t=table.open("source_table")
num_recs=t.records_get()
t.close()
' now, fill an array with the entire table
dim myptr_array[nrecs] as p
myptr_array.initialize_from_table("source_table")
' let's say you are summarizing the "balance" field for
' customers in NY
tot_balance=0
for i=1 to num_recs
if myptr_array[i].state="NY" then
tot_balance=tot_balance+myptr_array[i].balance
end if
next
ui_msg_box("total balance",""+tot_balance)

you should realize that there are functions already predefined in alpha five to do in one step what this script does. this script just illustrates how to use a pointer array.
e.g. i could replace the whole script with
total_balance=tablesum("source_table","state='NY'","balance")

i don't know if this helps you.

[Stan Mathews]

RE: How to Copy values of current record

FUNCTION Gather AS L ()
gather = .F.
tbl = table.current()
FOR i = 1 TO tbl.fields_get()
fld = tbl.field_get(i)
tbl.change_begin()
evaluate_template("tbl."+fld.name_get()+" = var->"+fld.name_get())
tbl.change_end(.T.)
NEXT I
gather = .T.
END FUNCTION

[John Panagia]

RE: How to Copy values of current record

Stan,

Thanks so much. These functions will prove very valuable to me. I guess I need to get comfortable with this eval_template thing, seems to provide a lot of power.

Thanks again,
John

[John Panagia]

RE: How to Copy values of current record

Peter,

Thanks for the code example. I thought of doing this kind of thing but wasn't sure how. Wouldn't a table containing many records create an out of memory situation? My files are usually in excess of 100,000 records.


Thanks,
John

[Stan Mathews]

RE: How to Copy values of current record

I'm sure you are aware, but will restate just in case...

These functions do not check to see if their counterpart has been issued -

you could gather() without having scatter() issued, consequences not yet investigated (error message?).

gather() does not check to see if the table that was scattered is still "table.current()", you could gather() to the wrong table if you allow opening another form based on another table, though only fields with names matching the original table would be affected. This may be the result you want.

Enjoy, with caution.