下面给出一个完整的例子，要注意的是：一开始需要将查询的字段全部加入TDBGrid中，否则会有访问冲突的。

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, Db, DBTables, Grids, DBGrids, StdCtrls, ExtCtrls, DBCtrls;

type
  TTFm_Main = class(TForm)
    qry_Data: TQuery;
    Ds_Data: TDataSource;
    Ed_Search: TEdit; //附加一个TEdit框.
    dbg_Data: TDBGrid;
    Database1: TDatabase; //数据库构件，试验时可任意设定。
    DBNavigator1: TDBNavigator;
    procedure dbg_DataTitleClick(Column: TColumn);
    procedure FormCreate(Sender: TObject);
    procedure Ed_SearchChange(Sender: TObject);

  private
  { Private declarations }
    FQueryStatement: string; // SQL 查询语句。
    FALphaNumericKeyPress: TKeyPressEvent;

  public
  { Public declarations }
    property QueryStatement: string read FQueryStatement;
    procedure FloatOnKeyPress(Sender: TObject; var Key: Char);
  end;

var
  TFm_Main: TTFm_Main;

implementation

{$R *.DFM}

procedure TTFm_Main.dbg_DataTitleClick(Column: TColumn);
var
  vi_Counter: Integer;
  vs_Field: string;
begin
  with dbg_Data do
  begin

  //First, deselect all the Grid Columns
    for vi_Counter := 0 to Columns.Count - 1 do
      Columns[vi_Counter].Color := clWindow;

  //Next "Select" the column the user has Clicked on
    Column.Color := clTeal;

  //Get the FieldName of the Selected Column
    vs_Field := Column.FieldName;

  //Order the Grid Data by the Selected column
    with qry_Data do
    begin
      DisableControls;
      Close;
      SQL.Clear;
      SQL.Text := QueryStatement + ' ORDER BY ' + vs_Field;
      Open;
      EnableControls;
    end;
  //Get the DataType of the selected Field and change the Edit event

  //OnKeyPress to the proper method Pointer
    case Column.Field.DataType of
      ftFloat: Ed_Search.OnKeyPress := FloatOnKeyPress;
    else
      Ed_Search.OnKeyPress := FALphaNumericKeyPress;
    end;
  end;
end;

procedure TTFm_Main.FloatOnKeyPress(Sender: TObject; var Key: Char);
begin
  if not (Key in ['0'..'9', #13, #8, #10, #46]) then
    Key := #0;
end;

procedure TTFm_Main.FormCreate(Sender: TObject);
begin

  //Keep a pointer for the default event Handler
  FALphaNumericKeyPress := Ed_Search.OnKeyPress;

  //Set the original Query SQL Statement
  FQueryStatement := 'SELECT * FROM your_table_name';

  //Select the first Grid Column
  dbg_DataTitleClick(dbg_Data.Columns[0]);
end;

procedure TTFm_Main.Ed_SearchChange(Sender: TObject);
var
  vi_counter: Integer;
  vs_Field: string;
begin
  try
    with dbg_Data do
    begin

  //First determine wich is the Selected Column
      for vi_Counter := 0 to Columns.Count - 1 do
        if Columns[vi_Counter].Color = clTeal then
        begin
          vs_Field := Columns[vi_Counter].FieldName;
          Break;
        end;

  //Locate the Value in the Query
      with qry_Data do
        case Columns[vi_Counter].Field.DataType of
          ftFloat: Locate(vs_Field, StrToFloat(Ed_Search.Text),
              [loCaseInsensitive, loPartialKey]);
        else
          Locate(vs_Field, Ed_Search.Text, [loCaseInsensitive, loPartialKey]);
        end;
    end;
  except
  end;
end;

end.

[1] [2] 下一页