demo.~dfm

计算字段实例,可以提取主要的字段加以计算

object Form1: TForm1
  Left = 246
  Top = 145
  Width = 558
  Height = 432
  Caption = #35745#31639#23383#27573#32534#31243#23454#20363
  Color = clBtnFace
  Font.Charset = GB2312_CHARSET
  Font.Color = clWindowText
  Font.Height = -15
  Font.Name = #26999#20307'_GB2312'
  Font.Style = []
  OldCreateOrder = False
  OnActivate = FormActivate
  PixelsPerInch = 120
  TextHeight = 15
  object Label1: TLabel
    Left = 32
    Top = 264
    Width = 48
    Height = 15
    Caption = #22269#23478#21517
  end
  object Label2: TLabel
    Left = 304
    Top = 264
    Width = 48
    Height = 15
    Caption = #39318#37117#21517
  end
  object Label3: TLabel
    Left = 32
    Top = 296
    Width = 48
    Height = 15
    Caption = #25152#22312#24030
  end
  object Label4: TLabel
    Left = 320
    Top = 296
    Width = 32
    Height = 15
    Caption = #38754#31215
  end
  object Label5: TLabel
    Left = 32
    Top = 328
    Width = 48
    Height = 15
    Caption = #20154#21475#25968
  end
  object Label6: TLabel
    Left = 264
    Top = 328
    Width = 96
    Height = 15
    Caption = #21333#20301#38754#31215#20154#21475
  end
  object DBGrid1: TDBGrid
    Left = 24
    Top = 16
    Width = 497
    Height = 233
    DataSource = DataSource1
    TabOrder = 0
    TitleFont.Charset = GB2312_CHARSET
    TitleFont.Color = clWindowText
    TitleFont.Height = -15
    TitleFont.Name = #26999#20307'_GB2312'
    TitleFont.Style = []
  end
  object Edit1: TEdit
    Left = 80
    Top = 256
    Width = 161
    Height = 23
    TabOrder = 1
    Text = 'Edit1'
  end
  object Edit2: TEdit
    Left = 360
    Top = 256
    Width = 161
    Height = 23
    TabOrder = 2
    Text = 'Edit2'
  end
  object Edit3: TEdit
    Left = 80
    Top = 288
    Width = 161
    Height = 23
    TabOrder = 3
    Text = 'Edit3'
  end
  object Edit4: TEdit
    Left = 360
    Top = 288
    Width = 161
    Height = 23
    TabOrder = 4
    Text = 'Edit4'
  end
  object Edit5: TEdit
    Left = 80
    Top = 320
    Width = 161
    Height = 23
    TabOrder = 5
    Text = 'Edit5'
  end
  object Edit6: TEdit
    Left = 360
    Top = 320
    Width = 161
    Height = 23
    TabOrder = 6
    Text = 'Edit6'
  end
  object Button1: TButton
    Left = 216
    Top = 360
    Width = 75
    Height = 25
    Caption = #36864#20986
    TabOrder = 7
    OnClick = Button1Click
  end
  object Table1: TTable
    BeforeScroll = Table1BeforeScroll
    AfterScroll = Table1AfterScroll
    OnCalcFields = Table1CalcFields
    DatabaseName = 'DBDEMOS'
    TableName = 'country.db'
    Left = 56
    Top = 88
    object Table1Name: TStringField
      FieldName = 'Name'
      Size = 24
    end
    object Table1Capital: TStringField
      FieldName = 'Capital'
      Size = 24
    end
    object Table1Continent: TStringField
      CustomConstraint = 'X = '#39'South America'#39' OR X = '#39'North America'#39
      ConstraintErrorMessage = 'Country is not in the American Continent'
      DefaultExpression = #39'South America'#39
      FieldName = 'Continent'
      Size = 24
    end
    object Table1Area: TFloatField
      FieldName = 'Area'
    end
    object Table1Population: TFloatField
      FieldName = 'Population'
    end
    object Table1ratio: TFloatField
      FieldKind = fkCalculated
      FieldName = 'ratio'
      Calculated = True
    end
  end
  object DataSource1: TDataSource
    DataSet = Table1
    Left = 160
    Top = 88
  end
end