Question

急！！c#ExecuteReader 要求已打开且可用的连接。连接的当前状态为已关闭。

public void ShowBook()
{
lvBook.Clear();
lvBook.Columns.Clear();
lvBook.Columns.Add("", 0);
lvBook.Columns.Add("书名", 220);
lvBook.Columns.Add("作者", 120);
lvBook.Columns.Add("价格", 60);
lvBook.Columns.Add("出版社", 300);
lvBook.Columns.Add("ISBN", 120);

conn = new SqlConnection(strConn);

sqlCmd = conn.CreateCommand();
sqlCmd.CommandText = "select bookid, bookname, author, press, price, ISBN from book";
sqlReader = sqlCmd.ExecuteReader();
conn.Open();
while (sqlReader.Read())
{
ListViewItem newlvi = new ListViewItem(sqlReader["bookid"].ToString().Trim());

newlvi.SubItems.Add(sqlReader["bookname"].ToString().Trim());
newlvi.SubItems.Add(sqlReader["author"].ToString().Trim());
newlvi.SubItems.Add(sqlReader["price"].ToString().Trim());
newlvi.SubItems.Add(sqlReader["press"].ToString().Trim());
newlvi.SubItems.Add(sqlReader["ISBN"].ToString().Trim());

lvBook.Items.Add(newlvi);
}

sqlReader.Close();
conn.Close();

lvBook.Items[0].Selected = true;
}

Answer 1

conn.Open();这句放到上面去.
conn = new SqlConnection(strConn);
conn.Open();

Answer 2

sqlReader.Close();
把这句换到别的地方去。