ClientDataSet FieldDefs Add Field

最新推荐文章于 2023-09-27 15:01:34 发布

原创最新推荐文章于 2023-09-27 15:01:34 发布 · 3.5k 阅读

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本文介绍如何在C++Builder中操作ClientDataSet的FieldDefs，讲解如何动态添加字段，创建内存中的虚拟表。

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ClientDataSet FieldDefs Add Field

void __fastcall TForm1::createField()
{
  ClientDataSet1->Close();

  ClientDataSet1->Fields->Clear();
  ClientDataSet1->FieldDefs->Clear();

  ClientDataSet1->Open();
  ClientDataSet1->Close();
  for(int i = 0 ;i < ClientDataSet1->Fields->Count - 1;i++)
   ClientDataSet1->Fields->Fields[0]->Free();//释放所有的静态字段
  for(int i = 0 ;i < ClientDataSet1->FieldDefs->Count - 1;i++)
    ClientDataSet1->FieldDefs->Items[i]->CreateField(ClientDataSet1);

  TBooleanField *NewField; 
  NewField = new TBooleanField(ClientDataSet1);
  NewField->FieldName="SelectMe";
  NewField->DisplayLabel = "选择";
  NewField->FieldKind=fkInternalCalc;
  NewField->DataSet=ClientDataSet1;
  NewField->Index = 0;
  ClientDataSet1->Open();
}

void __fastcall TForm1::BitBtn1Click(TObject *Sender)
{
        sql = "select  from TABLE1 ";
        this->ADOQuery1->Close();
        this->ADOQuery1->SQL->Clear();
        this->ADOQuery1->SQL->Add(this->sql);
        this->ADOQuery1->Open();
        this->createField();
}

ClientDataSet FieldDefs Add Field C++builder

  cds1->Close();  
  cds1->FieldDefs->Clear();
  cds1->FieldDefs->Add("ID", ftInteger, 0, true);
  cds1->FieldDefs->Add("Name", ftString, 20, false);
  cds1->FieldDefs->Add("DT", ftDateTime, 0, false);
  cds1->CreateDataSet();  
  cds1->AppendRecord(  ARRAYOFCONST((101,"aaa",Now().DateTimeString() )));
  cds1->AppendRecord(  ARRAYOFCONST((102,"bbb",Now().DateTimeString() )));
  cds1->AppendRecord(  ARRAYOFCONST((103,"ccc",Now().DateTimeString() )));

虚拟表内存表 for delphi

  ClientDataSet1.Close();
  ClientDataSet1.FieldDefs.Clear();
  ClientDataSet1.FieldDefs.Add('ID', ftInteger, 0, true);
  ClientDataSet1.FieldDefs.Add('Name', ftString, 20, false);
  ClientDataSet1.FieldDefs.Add('DT', ftDateTime, 0, false);
  ClientDataSet1.FieldDefs.Add('chk', ftBoolean, 0, false);
  ClientDataSet1.CreateDataSet();
  ClientDataSet1.Open;
  ClientDataSet1.Append;
  ClientDataSet1.FieldByName('id').Value := 101;
  ClientDataSet1.FieldByName('name').Value := 'abc';
  ClientDataSet1.FieldByName('dt').Value := Now;
  ClientDataSet1.Post;
  ClientDataSet1.AppendRecord([102,'bbb',Now()]);
  ClientDataSet1.AppendRecord([103,'ccc',Now()]);