Mega Code Archive
Incremental search in a DBGrid
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Title: Incremental search in a DBGrid
Question: When you fill a DBGrid with Data from a Query you can search for each column of the Grid, with a TEdit.
Answer:
Here is a sample project:
//MWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMW// Makes incremental search in a DBGrid with a TEdit
//MWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMW
unit U_Main;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
Db, DBTables, StdCtrls, Grids, DBGrids, ExtCtrls, DBCtrls;
type
TFm_Main = class(TForm)
Panel1: TPanel;
Panel2: TPanel;
qry_Data: TQuery;
Ds_Data: TDataSource;
dbg_Data: TDBGrid;
Label1: TLabel;
Ed_Search: TEdit;
Database1: TDatabase;
qry_DataNUM_FACTURA: TStringField;
qry_DataF_FACTURA: TDateTimeField;
qry_DataM_DEVENGADO: TFloatField;
DBNavigator1: TDBNavigator;
procedure dbg_DataTitleClick(Column: TColumn);
procedure FormCreate(Sender: TObject);
procedure Ed_SearchChange(Sender: TObject);
private
FQueryStatement: string;
//Since for Alphanumeric Field you dont need to validate nothing
//just keep a method pointer to the default Event Handler
FALphaNumericKeyPress: TKeyPressEvent;
public
property QueryStatement: string read FQueryStatement;
//Since we are going to search in various Fields wich DataType
//can be of diferent types, we must validate the user input on
//the OnkeyPress of the TEdit, but instead of building a super
//generic routine, lets make things simple. Build a separate
//method for each DataType you are interested in validate.
//I will only validate for Fields of type ftFloat, but you easily
//customize the code for your own needs..
//Method Pointer for Fields of DataType ftFloat
procedure FloatOnKeyPress(Sender: TObject; var Key: Char);
end;
var
Fm_Main: TFm_Main;
implementation
{$R *.DFM}
procedure TFm_Main.dbg_DataTitleClick(Column: TColumn);
var
vi_Counter: Integer;
vs_Field: String;
begin
with dbg_Data do
begin
//First, deselect all the Grids 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 Grids 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 Edits 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;//End of TFm_Main.dbg_DataTitleClick
//MWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMW
procedure TFm_Main.FloatOnKeyPress(Sender: TObject; var Key: Char);
begin
if not(Key in ['0'..'9', #13, #8, #10, #46]) then
Key := #0;
end;//End of TFm_Main.FloatOnKeyPress
//MWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMW
procedure TFm_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 FIELD1, FIELD2, FIELD3 '
'FROM ANYTABLE ';
//Select the first Grids Column
dbg_DataTitleClick(dbg_Data.Columns[0]);
end;//End of TFm_Main.FormCreate
//MWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMW
procedure TFm_Main.Ed_SearchChange(Sender: TObject);
var
vi_counter: Integer;
vs_Field: String;
begin
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;
end;//End of TFm_Main.Ed_SearchChange
//MWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMWMW
end.
So, you can customize the code to manage another DataTypes of TFields.
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