实现DBgrid点击标题栏排序！（仅库存提示部分，未完成）

TiShi.dfm

@@ -63,6 +63,7 @@ object Form6: TForm6
     TitleFont.Name = 'Tahoma'
     TitleFont.Style = []
     OnDrawColumnCell = DBGrid1DrawColumnCell
+    OnTitleClick = DBGrid1TitleClick
   end
   object DBGrid2: TDBGrid
     Left = 31

TiShi.pas

@@ -27,6 +27,7 @@ type
       Field: TField; State: TGridDrawState);
     procedure Button3Click(Sender: TObject);
     procedure Button4Click(Sender: TObject);
+    procedure DBGrid1TitleClick(Column: TColumn);
 
   private
     { Private declarations }
@@ -113,6 +114,54 @@ begin
   DBGrid1.DefaultDrawcolumnCell(Rect, DataCol, Column, State);
 end;
 
+procedure TForm6.DBGrid1TitleClick(Column: TColumn);
+var
+  SqlStr,myFieldName,TempStr: string;
+  OrderPos: integer;
+  SavedParams: TParams;
+begin
+  if not (Column.Field.FieldKind in [fkData,fkLookup]) then exit;
+  //如果字段类型不属于物理字段或查询字段则退出
+  if Column.Field.FieldKind =fkData then
+    myFieldName := UpperCase(Column.Field.FieldName)  //如为物理字段，字段名大写
+  else
+    myFieldName := UpperCase(Column.Field.KeyFields);   //如为查询字段，主键名大写
+
+  while Pos(myFieldName,';')<>0 do   //如果名称中包含分号
+    myFieldName := copy(myFieldName,1,Pos(myFieldName,';')-1)
+                  + ',' + copy(myFieldName,Pos(myFieldName,';')+1,100);  //把分号变逗号
+  with dm1.FDQuery7 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.Assign(SavedParams);
+      SavedParams.Free;
+    end;
+    Prepare;
+    Open;
+  end;
+end;
+
 procedure TForm6.DBGrid2DrawDataCell(Sender: TObject; const Rect: TRect;
   Field: TField; State: TGridDrawState);
 begin