点击DBGrid的Title对查询结果排序

//欲实现点击DBGrid的Title对查询结果排序，想作一个通用程序，不是一事一议，

//例如不能在SQL语句中增加Order by ...，因为SQL可能原来已经包含Order by ...，

//而且点击另一个Title时又要另外排序，目的是想作到象资源管理器那样随心所欲。

procedure TfrmChild.DBGrid1TitleClick(Column: TColumn);

var

SqlStr,myFieldName,TempStr: string;

OrderPos: integer;

SavedParams: TParams;

begin

if not (Column.Field.FieldKind in [fkData,fkLookup]) then exit;

if Column.Field.FieldKind =fkData then

myFieldName := UpperCase(Column.Field.FieldName)

else

myFieldName := UpperCase(Column.Field.KeyFields);

while Pos(myFieldName,';')<>0 do

myFieldName := copy(myFieldName,1,Pos(myFieldName,';')-1)

+ ',' + copy(myFieldName,Pos(myFieldName,';')+1,100);

with TQuery(TDBGrid(Column.Grid).DataSource.DataSet) do

begin

SqlStr := UpperCase(Sql.Text);

// if pos(myFieldName,SqlStr)=0 then exit;

if ParamCount>0 then

begin

SavedParams := TParams.Create;

SavedParams.Assign(Params);

end;

OrderPos := pos('ORDER',SqlStr);

if (OrderPos=0) or

(pos(myFieldName,copy(SqlStr,OrderPos,100))=0) then

TempStr := ' Order By ' + myFieldName + ' Asc'

else if pos('ASC',SqlStr)=0 then

TempStr := ' Order By ' + myFieldName + ' Asc'

else

TempStr := ' Order By ' + myFieldName + ' Desc';

if OrderPos<>0 then SqlStr := Copy(SqlStr,1,OrderPos-1);

SqlStr := SqlStr + TempStr;

Active := False;

Sql.Clear;

Sql.Text := SqlStr;

if ParamCount>0 then

begin

Params.AssignValues(SavedParams);

SavedParams.Free;

end;

Prepare;

Open;

end;