Delphi TQuery save to csv file - delphi

Question

I want to export content of a TQuery to a CSV file without using a 3d part component(Delphi 7). From my knowledge this can not be accomplished with Delphi standard components.
My solution was to save the content in a StringList with a CSV format, and save it to a file.
Is there any comfortable solution?
PS:I don't want to use JvCsvDataSet or any component. Question is: can this be accomplished only with Delphi 7 or higher standard components?
Thank you in advance!

Answer 1

Of course it can.
You just have to do the work to properly output the CSV content (quoting properly, handling embedded quotes and commas, etc.). You can easily write the output using TFileStream, and get the data using the TQuery.Fields and TQuery.FieldCount properly.
I'll leave the fancy CSV quoting and special handling to you. This will take care of the easy part:
var
Stream: TFileStream;
i: Integer;
OutLine: string;
sTemp: string;
begin
Stream := TFileStream.Create('C:\Data\YourFile.csv', fmCreate);
try
while not Query1.Eof do
begin
// You'll need to add your special handling here where OutLine is built
OutLine := '';
for i := 0 to Query.FieldCount - 1 do
begin
sTemp := Query.Fields[i].AsString;
// Special handling to sTemp here
OutLine := OutLine + sTemp + ',';
end;
// Remove final unnecessary ','
SetLength(OutLine, Length(OutLine) - 1);
// Write line to file
Stream.Write(OutLine[1], Length(OutLine) * SizeOf(Char));
// Write line ending
Stream.Write(sLineBreak, Length(sLineBreak));
Query1.Next;
end;
finally
Stream.Free; // Saves the file
end;
end;

Answer 2

The original question asked for a solution using a StringList. So it would be something more like this. It will work with any TDataSet, not just a TQuery.
procedure WriteDataSetToCSV(DataSet: TDataSet, FileName: String);
var
List: TStringList;
S: String;
I: Integer;
begin
List := TStringList.Create;
try
DataSet.First;
while not DataSet.Eof do
begin
S := '';
for I := 0 to DataSet.FieldCount - 1 do
begin
if S > '' then
S := S + ',';
S := S + '"' + DataSet.Fields[I].AsString + '"';
end;
List.Add(S);
DataSet.Next;
end;
finally
List.SaveToFile(FileName);
List.Free;
end;
end;
You can add options to change the delimiter type or whatever.

Answer 3

This is like the Rob McDonell solution but with some enhancements: header, escape chars, enclosure only when required, and ";" separator.
You can easily disable this enhancements if not required.
procedure SaveToCSV(DataSet: TDataSet; FileName: String);
const
Delimiter: Char = ';'; // In order to be automatically recognized in Microsoft Excel use ";", not ","
Enclosure: Char = '"';
var
List: TStringList;
S: String;
I: Integer;
function EscapeString(s: string): string;
var
i: Integer;
begin
Result := StringReplace(s,Enclosure,Enclosure+Enclosure,[rfReplaceAll]);
if (Pos(Delimiter,s) > 0) OR (Pos(Enclosure,s) > 0) then // Comment this line for enclosure in every fields
Result := Enclosure+Result+Enclosure;
end;
procedure AddHeader;
var
I: Integer;
begin
S := '';
for I := 0 to DataSet.FieldCount - 1 do begin
if S > '' then
S := S + Delimiter;
S := S + EscapeString(DataSet.Fields[I].FieldName);
end;
List.Add(S);
end;
procedure AddRecord;
var
I: Integer;
begin
S := '';
for I := 0 to DataSet.FieldCount - 1 do begin
if S > '' then
S := S + Delimiter;
S := S + EscapeString(DataSet.Fields[I].AsString);
end;
List.Add(S);
end;
begin
List := TStringList.Create;
try
DataSet.DisableControls;
DataSet.First;
AddHeader; // Comment if header not required
while not DataSet.Eof do begin
AddRecord;
DataSet.Next;
end;
finally
List.SaveToFile(FileName);
DataSet.First;
DataSet.EnableControls;
List.Free;
end;
end;

Answer 4

Delphi does not provide any built-in access to .csv data.
However, following the VCL TXMLTransform paradigm, I wrote a TCsvTransform class helper that will translate a .csv structure to /from a TClientDataSet.
As for the initial question that was to export a TQuery to .csv, a simple TDataSetProvider will make the link between TQuery and TClientDataSet.
For more details about TCsvTransform, cf http://didier.cabale.free.fr/delphi.htm#uCsvTransform