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#1 2017-05-30 19:11:25
Is there any way to simulate an ORDER BY for a TDynArray?
I bring some records from the database with a specific sort order and I put it in a record type vector. I need to add more items to this vector by keeping the initial ordering, however the records that are added are left at the end of the vector.
I want to know if there is any way to reorder this vector in the same way as it does in SQL ORDER BY.
(Sorry for my English)
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#3 2017-05-30 21:08:18
Re: Is there any way to simulate an ORDER BY for a TDynArray?
For more than one column/field?
Like this: "ORDER BY NAME, PRIORITY, DATEINI ASC"
I was able to do only with one column
Last edited by wendel (2017-05-30 21:19:30)
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#5 2017-05-31 17:35:08
Re: Is there any way to simulate an ORDER BY for a TDynArray?
I resolved passing this function to the Sort:
function OrderBy(const A, B): Integer;
function SortDateTime(const A, B): Integer;
begin
if TDateTime(A) < TDateTime(B) then
Result := -1
else
if TDateTime(A) > TDateTime(B) then
Result := 1
else
Result := 0;
end;
begin
Result := SortDynArrayInteger(TRec(A).USER_ID, TRec(B).CUSER_ID);
if Result = 0 then
begin
Result := SortDynArrayInteger(TRec(A).PRIORITY_ID, TRec(B).PRIORITY_ID);
if Result = 0 then
Result := SortDateTime(TRec(A).DATEINI, TRec(B).DATEINI);
end;
end;Offline
#6 2017-06-01 06:09:16
Re: Is there any way to simulate an ORDER BY for a TDynArray?
Another way to write it:
function OrderBy(const A,B): integer;
var ra: TRec absolute A;
rb: TRec absolute B;
begin
result := ra.USER_ID - rb.USER_ID;
if result <> 0 then
exit;
result := ra.PRIORITY_ID - rb.PRIORITY_ID;
if result <> 0 then
exit;
if ra.DATEINI < rb.DATEINI then
result := -1 else
if ra.DATEINI > rb.DATEINI then
result := 1;
end;The same comparison, but slightly faster, and perhaps easier to read/maintain.
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