Delphi编程时候诡异地出现ORA-00937错误，记录解决它的思路和方法

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, DB, ADODB;

type
  TForm1 = class(TForm)
    con1: TADOConnection;
    btn1: TButton;
    btn2: TButton;
    procedure FormCreate(Sender: TObject);
    procedure btn1Click(Sender: TObject);
    procedure btn2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  adoquery: TADOQuery;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  con1.Open;
  adoquery:= TADOQuery.Create(Application); 
  //这样的Create方式，adoquery会在程序关闭的时候销毁
  adoquery.Connection:= con1;
  //这个例子中的adoquery是一个全局变量
end;

procedure TForm1.btn1Click(Sender: TObject);  //这个按钮是使用Format拼接的SQL，然后执行 
var
  count: Integer;
  no, name: string;
begin
  adoquery.Close;
  no:= ‘testno‘;
  name:= ‘testname‘;
  adoquery.SQL.Text:= Format(‘select count(*) icount from practice where uno = ‘‘%s‘‘ and uname = ‘‘%s‘‘ ‘, [no, name]);
  try
    //注意因为可能会出现异常，所以最好是在这里捕捉一下异常，保证程序的稳健性
    adoquery.Open;
    adoquery.First;
    count:= adoquery.FieldByname(‘icount‘).AsInteger;
    ShowMessage(‘共有‘ + IntToStr(count) + ‘ 条记录‘);
  except
  on e:Exception do
    ShowMessage(e.Message);
  end;
end;

procedure TForm1.btn2Click(Sender: TObject);   //这个按钮是使用绑定变量的方法的SQL
var
  count: Integer;
  no, name: string;
begin
  adoquery.Close;
  no:= ‘testno‘;
  name:= ‘testname‘;
  adoquery.SQL.Text:= ‘select count(*) icount from practice where uno = :no  and uname = :name‘;
  adoquery.Parameters.ParamByName(‘no‘).Value:= no;
  adoquery.Parameters.ParamByName(‘name‘).Value:= name;
  //注意里面的绑定变量法的使用规范，这样的方式使用微软的Oracle驱动会报错
  //但是使用Oracle自己的驱动是OK的
  try
    //注意因为可能会出现异常，所以最好是在这里捕捉一下异常，保证程序的稳健性
    adoquery.Open;
    adoquery.First;
    count:= adoquery.FieldByName(‘icount‘).AsInteger;
    ShowMessage(‘一共有‘ + IntToStr(count) + ‘ 条记录‘);
  except
  on e:Exception do
    ShowMessage(e.Message);
  end;
end;

end.