Solved

ADO question

Posted on 2004-10-26
224 Views
Last Modified: 2013-11-23
Hello,

Here is my connection...

...
 Data := ExtractFilePath(Application.ExeName) + '\sales.mdb';
 try
  ADOConnection2.ConnectionString :=
            'Provider=Microsoft.Jet.OLEDB.4.0;' +
            'Data Source=' + Data +';'+
            'Persist Security Info=False';
...

From this I want to open a table called 'sales units' and populate Combobox3 with a list of the different text entries in the 'make' column.
From that, when a 'make' is selected, I want to load combobox4 with all the 'model' using a filterbyselection of combobox3.

I think I can figure it out from there, but it's been so long since I've had to do this, that I'm totally lost.  I don't want to use any special db components, I just want to do this programmatically. "no predefined db connection settings.

I hope I'm being clear...

Thanks,
Gabe
0
Question by:TherosEquipment
    10 Comments
     
    LVL 13

    Expert Comment

    by:BlackTigerX
    something like this...

    const
      CONN_STR='Provider=Microsoft.Jet.OLEDB.4.0;Data Source=%s;Persist Security Info=False';
    var
      Data:string;
      ADOTable:TADOTable;
    begin
      ADOTable:=TADOTable.Create(nil);
      try
        Data:=ExtractFilePath(Application.ExeName) + '\sales.mdb';
        ADOConnection2.ConnectionString:=Format(CONN_STR, [Data]);
        ADOConnection2.LoginPrompt:=False;

        ADOTable.Connection:=ADOConnection2;
        ADOTable.TableName:='SalesUnit';
        ADOTable.Active:=True;
        //do whatever you are going to do with your table here...
      finally
        ADOTable.Free
      end
    end;

    I created the ADOTable component dinamically, I don't know if you want that or to drop a component in the form...
    0
     

    Author Comment

    by:TherosEquipment
    looks pretty strait forward, but the real problem I have is getting the data after I make the connection.  see the last part of my question.

    Thanks
    0
     
    LVL 12

    Expert Comment

    by:esoftbg
    procedure TForm1.Button1Click(Sender: TObject);
    begin
      ADOQuery1.Active := False;
      ADOQuery1.Connection:=ADOConnection2;
      ADOQuery1.SQL.Text := 'SELECT DISTINCT make FROM sales_units';
      ADOQuery1.Active := True;
      ComboBox3.Clear;
      while not ADOQuery1.EOF do
        ComboBox3.Items.Add(ADOQuery1.FieldByName('make').AsString);
    end;
    0
     
    LVL 12

    Expert Comment

    by:esoftbg
    procedure TForm1.ComboBox3CloseUp(Sender: TObject);
    begin
      ADOQuery2.Active := False;
      ADOQuery2.Connection:=ADOConnection2;
      ADOQuery2.SQL.Text :=''
                         + 'SELECT DISTINCT model FROM sales_units'
                         + ' WHERE make = '
                         + '''' + ComboBox3.Text + ''''
                         + '';
      ADOQuery2.Active := True;
      ComboBox4.Clear;
      while not ADOQuery2.EOF do
        ComboBox4.Items.Add(ADOQuery2.FieldByName('model').AsString);
    end;
    0
     

    Author Comment

    by:TherosEquipment
    Ok,
    no compile errors, but the program hangs and does not paint to the screen.

    procedure TForm1.LoadComboBox3;
    const
      CONN_STR='Provider=Microsoft.Jet.OLEDB.4.0;Data Source=%s;Persist Security Info=False';
    var
      Data:string;
      ADOTable:TADOTable;
    begin
      ADOTable:=TADOTable.Create(nil);
      try
        Data:=ExtractFilePath(Application.ExeName) + '\sales.mdb';
        ADOConnection2.ConnectionString:=Format(CONN_STR, [Data]);
        ADOConnection2.LoginPrompt:=False;
        ADOTable.Connection:=ADOConnection2;
        ADOTable.TableName:='sales_units';
        ADOTable.Active:=True;
        //do whatever you are going to do with your table here...
        loadquery;
      finally
        ADOTable.Free
      end
    end;

    procedure TForm1.LoadQuery;
    begin
        combobox3.Clear;
      ADOQuery1.Active := False;
      ADOQuery1.Connection:=ADOConnection2;
      ADOQuery1.SQL.Text := 'SELECT DISTINCT make FROM sales_units';
      ADOQuery1.Active := True;
      while not ADOQuery1.EOF do
        ComboBox3.Items.Add(ADOQuery1.FieldByName('make').AsString);
    end;

    I like this, because I can understand it, but Isn't there a way to do this just by using the ADOTable?
    0
     
    LVL 12

    Expert Comment

    by:esoftbg
    > populate Combobox3 with a list of the different text entries in the 'make' column

    'SELECT DISTINCT make FROM sales_units' does exactly above requirements

    How to do it using ADOTable ?
    0
     

    Author Comment

    by:TherosEquipment
    esoftbg,

    Your solution is not producing the desired result.  The Count is right, but all the combobox items are the same (the first "make" in the list).

    for example...

    ComboBox3 should contain...

    Allen
    Imer
    Multiquip

    but I'm getting...

    Allen
    Allen
    Allen

    Sorry  :(
    0
     
    LVL 12

    Expert Comment

    by:esoftbg
    Oh, excuse me, I forgot something important:

      while not ADOQuery1.EOF do
      begin
        ComboBox3.Items.Add(ADOQuery1.FieldByName('make').AsString);
        ADOQuery1.Next; // it is very, very important !
      end;
    0
     

    Author Comment

    by:TherosEquipment
    esoftbg,

    Your solution works and the question is yours.
    Just one other thing...

    Can you help with the sql query for this...

    procedure TForm1.ComboBox4Change(Sender: TObject);
    begin
      ADOQuery2.Active := False;
      ADOQuery2.Connection:=ADOConnection2;
      ADOQuery2.SQL.Text :=''
                         + 'SELECT price AND list FROM sales_units'  //  << This is not working
                         + ' WHERE model = '
                         + '''' + ComboBox4.Text + ''''
                         + '';
      ADOQuery2.Active := True;
      label10.Caption := 'Price: $' + AdoQuery2.FieldByName('price').AsString;
      label11.Caption := 'List Price: $' + AdoQuery2.FieldByName('list').AsString;
    end;
    0
     
    LVL 12

    Accepted Solution

    by:
    procedure TForm1.ComboBox4CloseUp(Sender: TObject);
    begin
      ADOQuery2.Active := False;
      ADOQuery2.Connection:=ADOConnection2;
      ADOQuery2.SQL.Text :=''
                         + 'SELECT price, list FROM sales_units'
                         + ' WHERE model = '
                         + '''' + ComboBox4.Text + ''''
                         + '';
      ADOQuery2.Active := True;
      label10.Caption := 'Price: $' + AdoQuery2.FieldByName('price').AsString;
      label11.Caption := 'List Price: $' + AdoQuery2.FieldByName('list').AsString;
    end;
    0

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