Adding Delta functionality similar to TClientDataSet to Lazarus TDataSet

[szlbz]

The bufDataSet and MemDataSet that come with Lazarus lack the Delta functionality similar to TClientDataSet. This unit extends Delta from TDataSet, making it applicable to all TDataSet instances.   
 
How to use: 
1.Add DataSetDelta to the uses clause of your unit. 
2.xxxDataSet.ActivateMonitoring(true); //true--Enable the Delta functionality  false -- Stop Delta function
3.xxxDataSet.GetActionSQL(const ATableName: String; const AKeyFields: String = ''); // Generate SQL based on the Delta 
Note: 
Using GetActionSQL will clear the Delta records. 
 
How to use Delta with BufDataset: 
BufDataset1.ActivateMonitoring(true); // Enable the Delta functionality 
BufDataset1.GetActionSQL('test'); // Generate SQL based on the Delta 
=====================================================================

lazarus/fpc自带的bufDataSet和MemDataSet缺少类似TClientDataSet的Delta功能，这个单元从TDataSet扩展了Delta，可以直接生成相应的SQL，适用于所有TDataSet。
使用方法：
1、在unit的uses添加DataSetDelta
2、xxxDataSet.ActivateMonitoring(true)//启动Delta功能
3、xxxDataSet.GetActionSQL(const ATableName: String; const AKeyFields: String = '')//根据Delta返回相应的SQL

注意：
使用GetActionSQL后会清空Delta的记录

BufDataset使用Delta的方法：
BufDataset1.ActivateMonitoring(true)//启动Delta功能
BufDataset1.GetActionSQL('test');//根据Delta返回相应的SQL

https://github.com/szlbz/DataSetDelta.git

[bpranoto]

I tried the example, with Lazarus 3.5/fpc 3.2.2 on linux, unfortunately it doesn't compile:

1. Required package rtcsdk_fpc is not found

2. After delete rtcsdk_fpc requirement, compilation failed

Code: Pascal  [Select][+][-]

1. Compile Project, Target: /home/bambang/Downloads/lazarus/components/tbufdatasetdelta/DataSetDelta/project1: Exit code 1, Errors: 38, Warnings: 2, Hints: 37
2. Hint: Start of reading config file /home/bambang/lazarus_3.0.fixes/fpc/bin/x86_64-linux/fpc.cfg
3. Hint: End of reading config file /home/bambang/lazarus_3.0.fixes/fpc/bin/x86_64-linux/fpc.cfg
4. Verbose: Free Pascal Compiler version 3.2.2-r0d122c49 [2024/05/21] for x86_64
5. Verbose: Copyright (c) 1993-2021 by Florian Klaempfl and others
6. Verbose: Target OS: Linux for x86-64
7. Verbose: Compiling project1.lpr
8. Verbose: Compiling unit1.pas
9. Verbose: Compiling bufdataset.pas
10. bufdataset.pas(70,14) Note: Virtual method "Seek(LongInt;Word):LongInt;" has a lower visibility (protected) than parent class TStream (public)
11. bufdataset.pas(71,14) Note: Virtual method "Read(var <Formal type>;LongInt):LongInt;" has a lower visibility (protected) than parent class TStream (public)
12. bufdataset.pas(72,14) Note: Virtual method "Write(const <Formal type>;LongInt):LongInt;" has a lower visibility (protected) than parent class TStream (public)
13. bufdataset.pas(789,51) Hint: Parameter "size" not used
14. bufdataset.pas(793,15) Note: Call to subroutine "function AnsiStrLIComp(S1:PChar;S2:PChar;MaxLen:QWord):LongInt;" marked as inline is not inlined
15. bufdataset.pas(795,15) Note: Call to subroutine "function AnsiStrLComp(S1:PChar;S2:PChar;MaxLen:QWord):LongInt;" marked as inline is not inlined
16. bufdataset.pas(797,15) Note: Call to subroutine "function AnsiCompareText(const S1:AnsiString;const S2:AnsiString):LongInt;" marked as inline is not inlined
17. bufdataset.pas(799,15) Note: Call to subroutine "function AnsiCompareStr(const S1:AnsiString;const S2:AnsiString):LongInt;" marked as inline is not inlined
18. bufdataset.pas(802,55) Hint: Parameter "size" not used
19. bufdataset.pas(815,51) Hint: Parameter "size" not used
20. bufdataset.pas(815,66) Hint: Parameter "options" not used
21. bufdataset.pas(821,55) Hint: Parameter "size" not used
22. bufdataset.pas(821,70) Hint: Parameter "options" not used
23. bufdataset.pas(827,50) Hint: Parameter "size" not used
24. bufdataset.pas(827,65) Hint: Parameter "options" not used
25. bufdataset.pas(833,55) Hint: Parameter "size" not used
26. bufdataset.pas(833,70) Hint: Parameter "options" not used
27. bufdataset.pas(846,51) Hint: Parameter "size" not used
28. bufdataset.pas(846,66) Hint: Parameter "options" not used
29. bufdataset.pas(852,52) Hint: Parameter "size" not used
30. bufdataset.pas(852,67) Hint: Parameter "options" not used
31. bufdataset.pas(865,53) Hint: Parameter "size" not used
32. bufdataset.pas(865,68) Hint: Parameter "options" not used
33. bufdataset.pas(877,50) Hint: Parameter "size" not used
34. bufdataset.pas(877,65) Hint: Parameter "options" not used
35. bufdataset.pas(882,67) Hint: Parameter "options" not used
36. bufdataset.pas(887,55) Hint: Parameter "size" not used
37. bufdataset.pas(887,70) Hint: Parameter "options" not used
38. bufdataset.pas(1659,18) Error: Identifier not found "ftShortInt"
39. bufdataset.pas(1659,28) Error: Constant Expression expected
40. bufdataset.pas(1660,18) Error: Identifier not found "ftByte"
41. bufdataset.pas(1660,24) Error: Constant Expression expected
42. bufdataset.pas(1660,24) Error: duplicate case label
43. bufdataset.pas(1665,18) Error: Identifier not found "ftLongWord"
44. bufdataset.pas(1665,29) Error: Constant Expression expected
45. bufdataset.pas(1665,29) Error: duplicate case label
46. bufdataset.pas(1665,34) Error: identifier idents no member "AsLongWord"
47. bufdataset.pas(1665,49) Error: identifier idents no member "AsLongWord"
48. bufdataset.pas(1673,18) Error: Identifier not found "ftExtended"
49. bufdataset.pas(1673,29) Error: Constant Expression expected
50. bufdataset.pas(1673,29) Error: duplicate case label
51. bufdataset.pas(1673,34) Error: identifier idents no member "AsExtended"
52. bufdataset.pas(1673,49) Error: identifier idents no member "AsExtended"
53. bufdataset.pas(1674,18) Error: Identifier not found "ftSingle"
54. bufdataset.pas(1674,29) Error: Constant Expression expected
55. bufdataset.pas(1674,29) Error: duplicate case label
56. bufdataset.pas(1674,34) Error: identifier idents no member "AsSingle"
57. bufdataset.pas(1674,47) Error: identifier idents no member "AsSingle"
58. bufdataset.pas(2189,27) Hint: Variable "ACompareStruct" of a managed type does not seem to be initialized
59. bufdataset.pas(2539,5) Error: Identifier not found "ftShortint"
60. bufdataset.pas(2539,15) Error: Constant Expression expected
61. bufdataset.pas(2539,15) Error: duplicate case label
62. bufdataset.pas(2540,7) Error: Identifier not found "ftByte"
63. bufdataset.pas(2540,13) Error: Constant Expression expected
64. bufdataset.pas(2540,13) Error: duplicate case label
65. bufdataset.pas(2551,5) Error: Identifier not found "ftLongWord"
66. bufdataset.pas(2551,18) Error: Constant Expression expected
67. bufdataset.pas(2551,18) Error: duplicate case label
68. bufdataset.pas(2568,5) Error: Identifier not found "ftExtended"
69. bufdataset.pas(2568,18) Error: Constant Expression expected
70. bufdataset.pas(2568,18) Error: duplicate case label
71. bufdataset.pas(2569,5) Error: Identifier not found "ftSingle"
72. bufdataset.pas(2569,18) Error: Constant Expression expected
73. bufdataset.pas(2569,18) Error: duplicate case label
74. bufdataset.pas(2946,29) Warning: Symbol "ApplyRecUpdate" is deprecated
75. bufdataset.pas(3093,36) Error: Identifier not found "SErrUpdatesInProgess"
76. bufdataset.pas(4402,14) Hint: Local variable "s" of a managed type does not seem to be initialized
77. bufdataset.pas(4469,29) Hint: Local variable "Buf" does not seem to be initialized
78. bufdataset.pas(4475,18) Hint: Local variable "Buf" does not seem to be initialized
79. bufdataset.pas(4478,32) Hint: Variable "AUpdOrder" does not seem to be initialized
80. bufdataset.pas(4517,13) Warning: Implicit string type conversion from "AnsiString" to "UnicodeString"
81. bufdataset.pas(4518,48) Error: identifier idents no member "ReadUnicodeString"
82. bufdataset.pas(4526,24) Hint: Local variable "B" of a managed type does not seem to be initialized
83. bufdataset.pas(4578,20) Error: identifier idents no member "WriteUnicodeString"
84. bufdataset.pas(4601,14) Hint: Local variable "s" of a managed type does not seem to be initialized
85. bufdataset.pas(4799,0) Verbose: There were 38 errors compiling module, stopping
86. Verbose: Compilation aborted
87. Verbose: /home/bambang/lazarus_3.0.fixes/fpc/bin/x86_64-linux/ppcx64 returned an error exitcode
88.  

If it works, it will be very useful. Currently, I use TKbmMemTable for the same feature.

[szlbz]

Delete  rtcsdk_fpc

Project has been updated, please download again

[bpranoto]

Code: Pascal  [Select][+][-]

1. Hint: (11030) Start of reading config file /home/bambang/lazarus_3.0.fixes/fpc/bin/x86_64-linux/fpc.cfg
2. Hint: (11031) End of reading config file /home/bambang/lazarus_3.0.fixes/fpc/bin/x86_64-linux/fpc.cfg
3. Free Pascal Compiler version 3.2.2-r0d122c49 [2024/05/21] for x86_64
4. Copyright (c) 1993-2021 by Florian Klaempfl and others
5. (1002) Target OS: Linux for x86-64
6. (3104) Compiling project1.lpr
7. (3104) Compiling unit1.pas
8. (3104) Compiling DataSetDelta.pas
9. /home/bambang/Downloads/lazarus/components/tbufdatasetdelta/DataSetDelta/DataSetDelta.pas(81,39) Warning: (4046) Constructing a class "TBufDataset" with abstract method "LoadBlobIntoBuffer"
10. /home/bambang/lazarus_3.0.fixes/fpc/units/x86_64-linux/fcl-db/bufdataset.ppu:bufdataset.pas(620,15) Hint: (5062) Found abstract method: LoadBlobIntoBuffer(<TCustomBufDataset>;TFieldDef;PBufBlobField);
11. /home/bambang/Downloads/lazarus/components/tbufdatasetdelta/DataSetDelta/DataSetDelta.pas(95,39) Warning: (4046) Constructing a class "TBufDataset" with abstract method "LoadBlobIntoBuffer"
12. /home/bambang/lazarus_3.0.fixes/fpc/units/x86_64-linux/fcl-db/bufdataset.ppu:bufdataset.pas(620,15) Hint: (5062) Found abstract method: LoadBlobIntoBuffer(<TCustomBufDataset>;TFieldDef;PBufBlobField);
13. /home/bambang/Downloads/lazarus/components/tbufdatasetdelta/DataSetDelta/DataSetDelta.pas(78,27) Note: (5025) Local variable "LFieldValue" not used
14. /home/bambang/Downloads/lazarus/components/tbufdatasetdelta/DataSetDelta/DataSetDelta.pas(157,3) Note: (5025) Local variable "s" not used
15. /home/bambang/Downloads/lazarus/components/tbufdatasetdelta/DataSetDelta/DataSetDelta.pas(176,3) Note: (5025) Local variable "FieldDef" not used
16. /home/bambang/Downloads/lazarus/components/tbufdatasetdelta/DataSetDelta/DataSetDelta.pas(225,34) Error: (5000) Identifier not found "ftOraTimeStamp"
17. /home/bambang/Downloads/lazarus/components/tbufdatasetdelta/DataSetDelta/DataSetDelta.pas(294,41) Error: (4025) Incompatible type for arg no. 1: Got "Char", expected "Byte"
18. /home/bambang/lazarus_3.0.fixes/fpc/units/x86_64-linux/rtl/system.ppu:systemh.inc(1208,10) Hint: (5039) Found declaration: Chr(Byte):Char; InternProc;
19. /home/bambang/Downloads/lazarus/components/tbufdatasetdelta/DataSetDelta/DataSetDelta.pas(294,50) Error: (4025) Incompatible type for arg no. 1: Got "Char", expected "Byte"
20. /home/bambang/lazarus_3.0.fixes/fpc/units/x86_64-linux/rtl/system.ppu:systemh.inc(1208,10) Hint: (5039) Found declaration: Chr(Byte):Char; InternProc;
21. /home/bambang/Downloads/lazarus/components/tbufdatasetdelta/DataSetDelta/DataSetDelta.pas(316,53) Error: (4025) Incompatible type for arg no. 1: Got "Char", expected "Byte"
22. /home/bambang/lazarus_3.0.fixes/fpc/units/x86_64-linux/rtl/system.ppu:systemh.inc(1208,10) Hint: (5039) Found declaration: Chr(Byte):Char; InternProc;
23. /home/bambang/Downloads/lazarus/components/tbufdatasetdelta/DataSetDelta/DataSetDelta.pas(316,62) Error: (4025) Incompatible type for arg no. 1: Got "Char", expected "Byte"
24. /home/bambang/lazarus_3.0.fixes/fpc/units/x86_64-linux/rtl/system.ppu:systemh.inc(1208,10) Hint: (5039) Found declaration: Chr(Byte):Char; InternProc;
25. /home/bambang/Downloads/lazarus/components/tbufdatasetdelta/DataSetDelta/DataSetDelta.pas(320,98) Error: (4025) Incompatible type for arg no. 1: Got "Char", expected "Byte"
26. /home/bambang/lazarus_3.0.fixes/fpc/units/x86_64-linux/rtl/system.ppu:systemh.inc(1208,10) Hint: (5039) Found declaration: Chr(Byte):Char; InternProc;
27. /home/bambang/Downloads/lazarus/components/tbufdatasetdelta/DataSetDelta/DataSetDelta.pas(320,107) Error: (4025) Incompatible type for arg no. 1: Got "Char", expected "Byte"
28. /home/bambang/lazarus_3.0.fixes/fpc/units/x86_64-linux/rtl/system.ppu:systemh.inc(1208,10) Hint: (5039) Found declaration: Chr(Byte):Char; InternProc;
29. DataSetDelta.pas(338) Fatal: (10026) There were 7 errors compiling module, stopping
30. Fatal: (1018) Compilation aborted
31. Error: /home/bambang/lazarus_3.0.fixes/fpc/bin/x86_64-linux/ppcx64 returned an error exitcode
32.  
33.  

[bpranoto]

I fixed the errors. Here is the diff file to fix the compilation.

[szlbz]

已更新，在linux for aarch64 lazarus 3.4+fpc 3.2.2测试
请重新下载！
 please download again

[bpranoto]

It will be better if you make your class a descendant of TBuffDataSet instead of a helper class.

With your current approach, the FNewDataSet and FOldDataSet will never be freed, hence memory leaks will be occured.

If you make it as descendant class, you will be able to free them in the destructor.

[Thaddy]

It will be better if you make your class a descendant of TBuffDataSet instead of a helper class.

With your current approach, the FNewDataSet and FOldDataSet will never be freed, hence memory leaks will be occured.

If you make it as descendant class, you will be able to free them in the destructor.

There are several places where even the diff is not correct. you should use LineEnding or its alias LineBreak instead of #13#10 for cross platform reasons.
Also, version testing should be either a smaller than or greater than or equal expression and based on fpc_fullversion to avoid tying code to a specific single version:

Code: Pascal  [Select][+][-]

1. {$if fpc_fullversion >= 30301}
2. // specific code
3. writeln('trunk');
4. {$ifend}

That is I assume you are testing for Freepascal trunk, not Lazarus, because TbufDataset is fpc code, not lazarus code: only the component editor is Lazarus code. It may be that 3_3 resolves to the same, but that is bad coding. (I can't see that from the diff).

That said, it is a good idea.
Personally I would not derive or use a helper class: this code is better to integrate in the current class. Or even better in one of the ancestors as protected virtual abstract and then public override for implementation, but that is a lot more work. OTOH it gives the opportunity to implement delta functionality for all TCustomDataset descendants, which is a better design. The availability of delta functionality is actually not TBufDataset specific.

[szlbz]

It will be better if you make your class a descendant of TBuffDataSet instead of a helper class.

With your current approach, the FNewDataSet and FOldDataSet will never be freed, hence memory leaks will be occured.

If you make it as descendant class, you will be able to free them in the destructor.

xxxDataSet.ActivateMonitoring(false) ---会释放 FNewDataSet and FOldDataSet

[bpranoto]

Thank you Thaddy,

Also, version testing should be either a smaller than or greater than or equal expression and based on fpc_fullversion to avoid tying code to a specific single version:

Code: Pascal  [Select][+][-]

1. {$if fpc_fullversion >= 30301}
2. // specific code
3. writeln('trunk');
4. {$ifend}

That is I assume you are testing for Freepascal trunk, not Lazarus, because TbufDataset is fpc code, not lazarus code: only the component editor is Lazarus code. It may be that 3_3 resolves to the same, but that is bad coding. (I can't see that from the diff).

Thank you.

That said, it is a good idea.
Personally I would not derive or use a helper class: this code is better to integrate in the current class. Or even better in one of the ancestors as protected virtual abstract and then public override for implementation, but that is a lot more work. OTOH it gives the opportunity to implement delta functionality for all TCustomDataset descendants, which is a better design. The availability of delta functionality is actually not TBufDataset specific.

Yes, I agree.

[bpranoto]

It will be better if you make your class a descendant of TBuffDataSet instead of a helper class.

With your current approach, the FNewDataSet and FOldDataSet will never be freed, hence memory leaks will be occured.

If you make it as descendant class, you will be able to free them in the destructor.

xxxDataSet.ActivateMonitoring(false) ---会释放 FNewDataSet and FOldDataSet

There is a big possibility we forget to do this. Even in your example you don't do this.

 Try to compile with use heaptrc unit (-gh) you'll see the memory leaks.

[szlbz]

谢谢您的建议，已添加释放FNewDataSet和FOldDataSet
请重新下载！

Code: Pascal  [Select][+][-]

1. finalization
2.   FBeforeEdit:=nil;
3.   FBeforeDelete:=nil;
4.   FBeforeInsert:=nil;
5.   FAfterPost:=nil;
6.   Foldvalue:=nil;
7.   if FNewDataSet<>nil then
8.     freeandnil(FNewDataSet);
9.   if FOldDataSet<>nil then
10.     freeandnil(FOldDataSet);
11.  

[bpranoto]

FNewDataSet and FOldDataSet are regular variables, this mean no more than 1 instance of TBufDataSet can use this helper at the same time, right?

[szlbz]

helper class受限太多不能用于多个不同的DataSet，所以今天可以修改为：

Code: Pascal  [Select][+][-]

1. unit DataSetDelta;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, BufDataset, DB, TypInfo, Variants;
9.  
10. type
11.  
12.   TDataStateValue = (dsvOriginal, dsvDeleted, dsvInserted, dsvUpdated);
13.   TDataStateValues=set of TDataStateValue;
14.  
15.   TDataSetChangesMonitor =class(TComponent)
16.   private
17.     FDataState:TDataStateValue;
18.     Foldvalue:array of Variant;
19.     FBeforeEdit: TDataSetNotifyEvent;
20.     FBeforeDelete: TDataSetNotifyEvent;
21.     FBeforeInsert: TDataSetNotifyEvent;
22.     FAfterPost: TDataSetNotifyEvent;
23.     FNewDataSet:TBufDataSet;
24.     FOldDataSet:TBufDataSet;
25.     FDataSet:TDataSet;
26.     procedure CreateMonitorDataSet;
27.     procedure SetDataSet(AValue: TDataSet);
28.     procedure BeforeInserts(DataSet: TDataSet);
29.     procedure BeforeEdits(DataSet: TDataSet);
30.     procedure BeforeDeletes(DataSet:TDataSet);
31.     procedure AfterPosts(DataSet: TDataSet);
32.     function GetChangedCount:int64;
33.   public
34.     constructor Create(AOwner: TComponent); override;
35.     destructor Destroy; override;
36.     function GetActionSQL(const ATableName : String; const AKeyFields: String = ''): String;
37.     procedure ActivateMonitoring(AValue:Boolean =true);
38.     property ChangedCount:int64 read GetChangedCount;
39.     property DataSet:TDataSet read FDataSet write SetDataSet;
40.   end;
41.  
42. implementation

使用方法改为：

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.   Classes, SysUtils, BufDataset, DB, Forms, Controls, Graphics, Dialogs,
9.   DBGrids, StdCtrls,  Memds,TypInfo,Variants,DataSetDelta,lazutf8;
10.  
11. type
12.  
13.   { TForm1 }
14.  
15.   TForm1 = class(TForm)
16.     BufDataset1: TBufDataset;
17.     BufDataset2: TBufDataset;
18.     Button2: TButton;
19.     Button3: TButton;
20.     DataSource1: TDataSource;
21.     DataSource2: TDataSource;
22.     DBGrid1: TDBGrid;
23.     DBGrid2: TDBGrid;
24.     Memo1: TMemo;
25.     procedure Button2Click(Sender: TObject);
26.     procedure Button3Click(Sender: TObject);
27.     procedure FormClose(Sender: TObject; var CloseAction: TCloseAction);
28.     procedure FormCreate(Sender: TObject);
29.   private
30.   public
31.     dcm1:TDataSetChangesMonitor;
32.     dcm2:TDataSetChangesMonitor;
33.   end;
34.  
35. var
36.   Form1: TForm1;
37.  
38. implementation
39.  
40. {$R *.lfm}
41.  
42. { TForm1 }
43.  
44. procedure TForm1.Button2Click(Sender: TObject);
45. var sql:string;
46. begin
47.   if BufDataset1.State in [dsEdit, dsInsert] then
48.     BufDataset1.Post;
49.   sql:=dcm1.GetActionSQL('test');
50.   if sql<>'' then
51.     memo1.Lines.Add(sql);
52. end;
53.  
54. procedure TForm1.Button3Click(Sender: TObject);
55. var sql:string;
56. begin
57.   if BufDataset2.State in [dsEdit, dsInsert] then
58.     BufDataset2.Post;
59.   sql:=dcm2.GetActionSQL('demo');
60.   if sql<>'' then
61.     memo1.Lines.Add(sql);
62. end;
63.  
64. procedure TForm1.FormClose(Sender: TObject; var CloseAction: TCloseAction);
65. begin
66.   if Assigned(dcm1) then freeandnil(dcm1);
67.   if Assigned(dcm2) then freeandnil(dcm2);
68. end;
69.  
70. procedure TForm1.FormCreate(Sender: TObject);
71. begin
72.   BufDataset1.FieldDefs.Clear;
73.   BufDataset1.FieldDefs.Add('test1', TFieldType(GetEnumValue(TypeInfo(TFieldType), 'ftString')), 30);
74.   BufDataset1.FieldDefs.Add('test2', TFieldType(GetEnumValue(TypeInfo(TFieldType), 'ftinteger')));
75.   BufDataset1.CreateDataset;
76.  
77.   BufDataset2.FieldDefs.Clear;
78.   BufDataset2.FieldDefs.Add('test11', TFieldType(GetEnumValue(TypeInfo(TFieldType), 'ftString')), 30);
79.   BufDataset2.FieldDefs.Add('test12', TFieldType(GetEnumValue(TypeInfo(TFieldType), 'ftinteger')));
80.   BufDataset2.FieldDefs.Add('test13', TFieldType(GetEnumValue(TypeInfo(TFieldType), 'ftinteger')));
81.   BufDataset2.CreateDataset;
82.  
83.   memo1.Lines.Clear;
84.   BufDataset2.Open;
85.   BufDataset1.Open;
86.  
87.   dcm1:=TDataSetChangesMonitor.Create(self);
88.   dcm2:=TDataSetChangesMonitor.Create(self);
89.   dcm1.DataSet:=BufDataset1; //监控BufDataset1的数据变化
90.   dcm2.DataSet:=BufDataset2; //监控BufDataset2的数据变化
91.   dcm1.ActivateMonitoring(true);
92.   dcm2.ActivateMonitoring;
93. end;
94.  
95. end.
96.  

如需要的请重新下载！

[bpranoto]

看去来更好!