Question

无法将类型“System.Data.SqlClient.SqlDataReader”隐式转换为“System.DateTime”

DateTime res;
string mycnn = "Data Source=.;Initial Catalog=HotelReservation;Integrated Security=True";
SqlConnection myconnection = new SqlConnection(mycnn);
string str = "select Max(Outtime) from Dingdan where Room='"+ DropDownList2.SelectedItem.Value+"'";
SqlCommand mycommand = new SqlCommand(str,myconnection);
mycommand.Connection.Open();
SqlDataReader myreader = mycommand.ExecuteReader();
if (myreader.Read())
{
res = mycommand.ExecuteReader();
}
else
{
Page.RegisterStartupScript("", "<script>alert('该房间在该时间已经被预定！')</script>");
mycommand.Connection.Close();

}
return res;

Answer 1

把mycommand.ExecuteReader();
改为：
res = (DateTime)myreader[0];
myreader.Close();//记得加这句，不然可能会出错。

Answer 2

if (myreader.Read())
{
res = mycommand.ExecuteReader();
}
修改 res=myreader.GetDateTime(int i); i为取得的索引号

Answer 3

//改为
if (myreader.Read())
{
res = DateTime.Parse(myreader["数据库中要查询的列名"]);
}
//最后要加myreader.Close();