为什么我的这句话包未将设置对象引用到实例Database database = DatabaseFactory.CreateDatabase()

   string SQL = "";
        Database database = DatabaseFactory.CreateDatabase();
        try
        {
            SQL = "if  exists(select * from sysobjects where id=object_id('ExcelToData')) drop table ExcelToData";
            DbCommand dbcommand = database.GetSqlStringCommand(SQL);
            database.ExecuteNonQuery(dbcommand);
            SQL = "select * into ExcelToData";
            SQL += " FROM OpenDataSource( 'Microsoft.Jet.OLEDB.12.0','Data Source=\"" + strDataFilePath + "\";User ID=sa;Password=sa;Extended properties=Excel 12.0')...[Sheet1$]";
            DbCommand dbcommand1 = database.GetSqlStringCommand(SQL);
            database.ExecuteNonQuery(dbcommand1);