Componentes.Terceros.RemObjects/internal/5.0.24.615/1/Data Abstract for Delphi/Samples/SQL Access/SQLAccessMain.pas

unit SQLAccessMain;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, uDADriverManager, uDAEngine, uDAADODriver, uDAClasses, StdCtrls,
  DB, uDADataTable, uDACDSDataTable, uDAADODataTable, ExtCtrls,
  ComCtrls, uDAScriptingProvider;

type
  TSQLAccessMainForm = class(TForm)
    DriverManager: TDADriverManager;
    DAADODriver: TDAADODriver;
    PageControl1: TPageControl;
    TabSheet1: TTabSheet;
    TabSheet2: TTabSheet;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    ExecuteButton: TButton;
    Memo: TMemo;
    rgConnections: TRadioGroup;
    eID: TEdit;
    eCompanyName: TEdit;
    ePhoneNumber: TEdit;
    ProcessSQLButton: TButton;
    Memo1: TMemo;
    Memo2: TMemo;
    rgProcessors: TRadioGroup;
    cbOrderBy: TComboBox;
    Label4: TLabel;
    DAConnectionManager: TDAConnectionManager;
    Panel1: TPanel;
    DASchema: TDASchema;
    procedure ExecuteButtonClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure ProcessSQLButtonClick(Sender: TObject);

  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  SQLAccessMainForm: TSQLAccessMainForm;

implementation

uses uDAInterfaces, uDAMacroProcessors, uDAMacros;

{$R *.dfm}

procedure TSQLAccessMainForm.ExecuteButtonClick(Sender: TObject);
var
  connname: string;
  conn: IDAConnection;
  ds: IDADataset;
  i: integer;
  orderby: integer;
begin
  { In this example we are treating two different SQL queries like they were the same one.
    One takes data from the SHIPPERS table when the other from the CUSTOMERS one. The field mappings
    that are used when building the where clause isolate the developer from the SQL details and allow
    you to build fairly complex where clauses without the need to do string concatenations in code.

    Examine the two sql statements associated with the Customers dataset for the two connections for
    more details. The code below transparently works for both.

    IMPORTANT: Keep in mind the SQL property of a dataset will always and only reflect the statement you define
    in the statement and the dynamic WHERE clause will only be merged to it when opening the dataset.
  }

  Memo.Lines.Add('---------------');
  Memo.Lines.Add('');
  try
    connname := Trim(Copy(rgConnections.Items[rgConnections.ItemIndex], 1, Pos('-', rgConnections.Items[rgConnections.ItemIndex]) - 1));
    conn := DAConnectionManager.NewConnection(connname, TRUE);

    ds := DASchema.NewDataset(conn, 'Customers');

    { Note: we could have also created the dataset along with the field mappings and statements manually via code.
            In some extremely dynamic situations that might be preferrable. }

    Memo.Lines.Add('Mappings');
    for i := 0 to ds.FieldCount - 1 do
      Memo.Lines.Add(ds.fields[i].TableField + ' --> ' + ds.fields[i].Name);
    Memo.Lines.Add('');

    ds.Where.AddCondition('ID', cLike, eID.Text);

    if (eCompanyName.Text <> '') and (ds.Where.Clause <> '') then ds.Where.AddOperator(opAND);

    ds.Where.AddCondition('CompanyName', cDifferent, eCompanyName.Text);

    if (ePhoneNumber.Text <> '') and (ds.Where.Clause <> '') then ds.Where.AddOperator(opOR);

    ds.Where.AddCondition('PhoneNumber', cEqual, ePhoneNumber.Text);

    orderby := POS('order by', lowercase(ds.SQL));

    if (orderby = 0) then begin
      if (cbOrderBy.Text <> '') then ds.SQL := ds.SQL + ' ORDER BY ' + ds.Fieldbyname(cbOrderBy.Text).TableField;
    end
    else begin
      if (cbOrderBy.Text = '') then ds.SQL := copy(ds.sql, 1, orderby - 1)
      else
        ds.SQL := copy(ds.sql, 1, orderby - 1) + ' ORDER BY ' + ds.Fieldbyname(cbOrderBy.Text).TableField;
    end;
    ds.Open;
  finally
    Memo.Lines.Add('SQL >>> ' + ds.SQL);
    Memo.Lines.Add('WHERE >>> ' + ds.Where.Clause);
  end;
end;

procedure TSQLAccessMainForm.FormCreate(Sender: TObject);
var
  i: integer;
  conn: IDAConnection;
  ds: IDADataset;
begin
  with DAConnectionManager do
    for i := 0 to (Connections.Count - 1) do begin
      rgConnections.Items.Add(Connections[i].Name + ' - ' + Connections[i].Description);
    end;

  rgConnections.ItemIndex := 0;

  conn := DAConnectionManager.NewConnection('NorthwindCustomers');
  ds := DASchema.NewDataset(conn, 'Customers');
  cbOrderBy.Items.Add('');
  for i := 0 to (ds.FieldCount - 1) do begin
    cbOrderBy.Items.Add(ds.Fields[i].Name);
  end;
end;

procedure TSQLAccessMainForm.ProcessSQLButtonClick(Sender: TObject);
var
  processor: TDASQLMacroProcessor;
  savedShortDateFormat: string;
  SavedDateSeparator, savedTimeSeparator: Char;
begin
  case rgProcessors.ItemIndex of
    0: processor := TDAMSSQLMacroProcessor.Create;
    1: processor := TDAIBMacroProcessor.Create;
    2: processor := TDAOracleMacroProcessor.Create;
    3: processor := TDADBISAMMacroProcessor.Create;
  else Exit;
  end;
  savedShortDateFormat := ShortDateFormat;
  savedDateSeparator := DateSeparator;
  savedTimeSeparator := TimeSeparator;
  try
    ShortDateFormat := 'MM/DD/YYYY';
    DateSeparator := '/';
    TimeSeparator := ':';
    Memo2.Lines.Text := processor.Eval(Memo1.Lines.Text)
  finally
    ShortDateFormat := savedShortDateFormat;
    DateSeparator := savedDateSeparator;
    TimeSeparator := savedTimeSeparator;
    processor.Free;
  end;
end;

end.