Talk to a MSAccess database thru Dot Net
A working Delphi for Dot Net example that talks to an MSAccess
database and displays one result. This code should properly
demonstrate the use of Dot Net Components to retreive Data from
MS Access. Other examples I’ve seen are Internet based and do not
function correctly.
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program DBTest; uses System.Windows.Forms, Newform2 in 'c:\tempnet\Newform2.pas' {Form1}; begin Mainform := TForm1.Create; Application.Run(Mainform); end. //-------------------------------------------------------------------- // Unit refered to by the main program. Make sure your database // path is set correctly //-------------------------------------------------------------------- unit NewForm2; interface uses { Just like the old uses clause in a delphi program. The SYSTEM namespace refers to windows type controls and not specifically the delphi ones. To draw a delphi button call on the BORLAND.VCL name spaces... see below } System.Reflection, System.Drawing, System.Drawing.Text, System.ComponentModel, System.Windows.Forms, System.Data.OleDB, System.Data, System.Data.Common, System.Runtime.InteropServices; type TForm1 = class(Form) private buttonload: system.windows.forms.button; // a button Components: system.componentmodel.container; // a component store datagrid1: system.windows.forms.datagrid; // not used in this implementation public constructor Create; // which I will inherite and amend procedure InitializeComponents; // easy way to centralise component creation procedure Button1_Click(Sender: TObject; E: EventArgs); // on click event end; var MainForm: TForm1; // as ever a main delphi form implementation constructor TForm1.Create; begin inherited Create; // normal create stuff then set up all the required components InitializeComponents; // sets up components end; procedure TForm1.InitializeComponents; var MyControls: array[0..2] of control; // container class for main form begin Self.ClientSize := system.Drawing.Size.Create(600,413); // client window on screen Self.Components := System.ComponentModel.Container.Create(); // container class for the other bits Self.buttonload := system.windows.forms.button.Create(); // make a button Self.buttonload.add_click(button1_click); // set its on click event Self.buttonload.Size := system.drawing.Size.Create(112,32); // size up the button Self.buttonload.location := system.drawing.point.Create(480,352); // where on screen ? Self.buttonload.Text := 'Read the database'; // text on the button - 'caption' in real delphi Self.datagrid1 := system.windows.forms.datagrid.Create(); // draw a datagrid - not used Self.datagrid1.Size := system.drawing.Size.Create(584,336); Self.datagrid1.location := system.drawing.point.Create(8,8); MyControls[0] := Self.buttonload; // add button to container class MyControls[1] := Self.datagrid1; // add grid to container class Self.Controls.AddRange(MyControls); // basically add them to the form, form is now parent end; procedure TForm1.Button1_Click(Sender: TObject; E: EventArgs); var dbConnection: oleDBConnection; dbCommand: OleDBCommand; dbReader: OleDBDataReader; dbDataAdapter: OleDBDataAdapter; dbDataset: Dataset; temp, temp1: string; int1: Integer; begin temp := 'Provider=Microsoft.Jet.OLEDB.4.0;Data Source=db1.mdb'; // connection string temp1 := 'Select * from Shawbury'; // SQL code to fire (* Found that I had to use an explicit string to make the connection , The exapmple code was'not very clear on this - it works, so hopefully it's the right solution *) dbConnection := System.Data.OleDB.OleDbConnection.Create(temp); // make a DB Connection dbConnection.Open(); // open a DB Conection dbCommand := System.Data.OleDB.OleDbCommand.Create(temp1, dbConnection); // execute the SQL dbReader := dbCommand.ExecuteReader(); // and store in a datareader int1 := dbReader.GetOrdinal('subcol1'); // I have a coloum in the Database called subcol1 while dbReader.read() do // keep reading all records begin // gives you a warm feeling to see the last record on the button // - now I'm sure its read the file buttonload.Text := dbreader.GetValue(int1).tostring; end; end; end. |