Author: Vladimir Orlenko
Some times we need send hugo quantity of data from MiddleWare Server to client
application. If we do it one portion than user mast wait long time, but we can send
this data by portions, when user is needed in it.
Answer:
Some times we need send hugo quantity of data from MiddleWare Server to client
application. If we do it one portion than user mast wait long time, but we can send
this data by portions, when user is needed in it.
This is sample about getting portion of data from DataSetProvider and adding it to
CLientDataSet.
In my article "Accessing DataBase via 3th server" you can read how send data
between applications usin INDY components.
1 unit Unit1;
2
3 interface
4
5 uses
6 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
7 Dialogs, StdCtrls, Buttons, DB, DBTables, Provider, DBClient, Grids,
8 DBGrids, ExtCtrls, DBCtrls, IdBaseComponent,
9 IdAntiFreezeBase, IdAntiFreeze, JvSpecialProgress;
10
11 type
12 TForm1 = class(TForm)
13 DataSetProvider1: TDataSetProvider;
14 Table1: TTable;
15 BitBtn1: TBitBtn;
16 DBGrid1: TDBGrid;
17 DBGrid2: TDBGrid;
18 DataSource1: TDataSource;
19 DataSource2: TDataSource;
20 ClientDataSet1: TClientDataSet;
21 BitBtn2: TBitBtn;
22 DBNavigator1: TDBNavigator;
23 IdAntiFreeze1: TIdAntiFreeze;
24 BitBtn3: TBitBtn;
25 JvSpecialProgress1: TJvSpecialProgress;
26 procedure BitBtn1Click(Sender: TObject);
27 procedure FormShow(Sender: TObject);
28 procedure BitBtn2Click(Sender: TObject);
29 procedure DBNavigator1Click(Sender: TObject; Button: TNavigateBtn);
30 procedure BitBtn3Click(Sender: TObject);
31 private
32 { Private declarations }
33 public
34 { Public declarations }
35 data: OleVariant;
36 records: integer;
37 end;
38
39 var
40 Form1: TForm1;
41
42 implementation
43
44 {$R *.dfm}
45
46 procedure TForm1.BitBtn1Click(Sender: TObject);
47 var
48 recs: integer;
49 j: integer;
50 begin
51 ClientDataSet1.Active := False;
52 data := DataSetProvider1.GetRecords(1, recs, ResetOption + MetaDataOption);
53 Showmessage(format('get %d Records', [recs, i]));
54 ClientDataSet1.AppendData(data, False);
55 ClientDataSet1.Active := True;
56
57 end;
58
59 procedure TForm1.FormShow(Sender: TObject);
60 begin
61 records := DataSetProvider1.DataSet.RecordCount;
62 end;
63
64 procedure TForm1.BitBtn2Click(Sender: TObject);
65 var
66 recs: integer;
67 j: integer;
68 begin
69 data := DataSetProvider1.GetRecords(-1, recs, ResetOption + MetaDataOption);
70 ClientDataSet1.AppendData(data, False);
71 ClientDataSet1.Active := True;
72 end;
73
74 procedure TForm1.DBNavigator1Click(Sender: TObject; Button: TNavigateBtn);
75 var
76 recs: integer;
77 begin
78
79 case Button of
80 nbNext:
81 begin
82 if DBNavigator1.DataSource.DataSet.RecordCount data :=
83 DataSetProvider1.GetRecords(1, recs, ResetOption + MetaDataOption);
84 ClientDataSet1.AppendData(data, False);
85 end;
86 end;
87 nbPrior:
88 begin
89 end;
90 nbLast:
91 begin
92 if DBNavigator1.DataSource.DataSet.RecordCount data :=
93 DataSetProvider1.GetRecords(-1, recs, ResetOption + MetaDataOption);
94 ClientDataSet1.AppendData(data, False);
95 end;
96 end;
97 nbFirst:
98 begin
99 end;
100 end;
101
102 end;
103
104 procedure TForm1.BitBtn3Click(Sender: TObject);
105 var
106 recs: integer;
107 begin
108 JvSpecialProgress1.Maximum := records;
109 JvSpecialProgress1.Position := 1;
110 while ClientDataSet1.RecordCount data := DataSetProvider1.GetRecords(1, recs,
111 ResetOption + MetaDataOption);
112 ClientDataSet1.AppendData(data, False);
113 JvSpecialProgress1.Position := JvSpecialProgress1.Position + 1;
114 end;
115 end;
116
117 end.
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