[英]Cannot implicitly convert type 'System.Collections.Generic.List<ValueObjectLayer.booksVAL>' to 'int'
I'm trying to make a 3 layered C# Library Management project.我正在尝试制作一个 3 层 C# 图书馆管理项目。
I'm trying to select a book from bookDAL (dataacceslayer) through booksBLL(businesslogiclayer and show it on winforms.我正在尝试 select 一本从 bookDAL(dataacceslayer)到 bookBLL(businesslogiclayer)的书,并在 winforms 上显示。
i get this error message on BLL error我收到有关 BLL错误的此错误消息
DAL:达尔:
public static List<booksVAL> BookSelect(string x)
{
List<booksVAL> sonuc = new List<booksVAL>();
OleDbCommand cmdkitaplistele = new OleDbCommand("select * from books where id = " + Int32.Parse(x) + " ", dbConnection.conn); //
if (cmdkitaplistele.Connection.State != ConnectionState.Open) // bağlantı açık değise
{
cmdkitaplistele.Connection.Open(); // bağlantıyı aç
}
OleDbDataReader dr = cmdkitaplistele.ExecuteReader(); // sorgu sonuçlarını data reader ile oku
while (dr.Read())
{
booksVAL book = new booksVAL();
book.bookId = int.Parse(dr["id"].ToString());
book.bookName = dr["bookname"].ToString();
book.bookAuthor = dr["authorname"].ToString();
book.bookPagecount = dr["pagecount"].ToString();
book.bookDatepublished = dr["datepublished"].ToString();
book.bookIsavailable = dr["isavailable"].ToString();
book.bookCategory = dr["category"].ToString();
sonuc.Add(book);
}
dr.Close();
return sonuc;
}
BLL: BLL:
public static int BookSelect(string x)
{
return booksDAL.BookSelect(x);
Form:形式:
public partial class bookupdateForm : Form
{
booksForm f1;
public bookupdateForm(booksForm frm1)
{
InitializeComponent();
this.f1 = frm1;
booksBLL.BookSelect(f1.selectedlabel.Text); // selectedlabel comes from another form, it works
}
}
Problem is here:问题在这里:
public static int BookSelect(string x)
{
return booksDAL.BookSelect(x);
}
Change return type int
to List<booksVAL>
:将返回类型
int
更改为List<booksVAL>
:
public static List<booksVAL> BookSelect(string x)
{
return booksDAL.BookSelect(x);
}
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