我尝试将SQL Results保存在数组中并将其返回。但我得到一个例外：数组超出范围错误。
这是我的代码：
public BookingUpdate[] getBookingUpdates(string token)
{
String command = "SELECT b.ID,b.VERANSTALTER, rr.VON ,rr.BIS, b.THEMA, b.STORNO, ra.BEZEICHNUNG from BUCHUNG b JOIN RESERVIERUNGRAUM rr on rr.BUCHUNG_ID = b.ID JOIN RAUM ra on ra.ID = rr.RAUM_ID WHERE b.UPDATE_DATE BETWEEN DATEADD (DAY , -20 , getdate()) AND getdate() AND b.BOOKVERNR = 0";
SqlConnection connection = new SqlConnection(GetConnectionString());
BookingUpdate[] bookingupdate = new BookingUpdate[1];
connection.Open();
try
{
SqlCommand cmd = new SqlCommand(command, connection);
SqlDataReader rdr = null;
int count = 0;
rdr = cmd.ExecuteReader();
while (rdr.Read())
{
DataTable dt = new DataTable();
dt.Load(rdr);
count = dt.Rows.Count;
for (int c = 0; c < count; c++)
{
bookingupdate = new BookingUpdate[c];
bookingupdate[c].bookingID = (long)rdr["ID"]; // <---- Error is here
bookingupdate[c].fullUserName = rdr["VERANSTALTER"].ToString();
bookingupdate[c].newStart = (DateTime)rdr["VON"];
bookingupdate[c].newStart = (DateTime)rdr["BIS"];
bookingupdate[c].newSubject = rdr["THEMA"].ToString();
bookingupdate[c].newlocation = rdr["BEZEICHNUNG"].ToString();
if (rdr["STORNO"].ToString() != null)
{
bookingupdate[c].deleted = true;
}
else
{
bookingupdate[c].deleted = false;
}
}
}
}
catch (Exception ex)
{
log.Error(ex.Message + "\n\rStackTrace:\n\r" + ex.StackTrace);
}
finally
{
connection.Close();
}
return bookingupdate;
}
我缺少什么？
答案 0 :(得分：2)
bookingupdate = new BookingUpdate[c];
bookingupdate[c].bookingID = (long)rdr["ID"];
您正在创建一个长度为c的数组，这意味着它具有索引0 to (c-1) - 然后当您尝试存储在位置c时，您将超出范围。
答案 1 :(得分：1)
Imho我将使用Linq简化你构建该数组的方法：
BookingUpdate[] bookingupdate = dt.AsEnumerable()
.Select(r => new BookingUpdate{
bookingID = r.Field<long>("ID"),
fullUserName = r.Field<string>("VERANSTALTER"),
newStart = r.Field<DateTime>("Von"),
newEnd = r.Field<DateTime>("Bis"), // here was another bug in your originalcode
newSubject = r.Field<string>("THEMA"),
newlocation = r.Field<string>("BEZEICHNUNG"),
deleted = r.Field<string>("STORNO") != null
})
.ToArray();
通过这种方式，您不会遇到超出界限的数组问题。
答案 2 :(得分：1)
您似乎正在使用
为数组创建和分配内存bookingupdate = new BookingUpdate[c];
但实际上并没有创建BookingUpdate的实例。当您尝试在数组元素上设置属性时，没有实际的BookingUpdate要更新 - 只有一个持有者。
我建议将代码改为：
...
bookingupdate = new BookingUpdate[count]; // allocates space for the number of BookingUpdates to be created
for (int c = 0; c < count; c++)
{
bookingupdate[c] = new BookingUpdate(); // create a new instance of BookingUpdate and assign it the array
bookingupdate[c].bookingID = (long)rdr["ID"];
...
我希望这有帮助！
答案 3 :(得分：0)
您访问超出范围的n元素数组的第n个元素，您需要访问n - 1元素。
bookingupdate = new BookingUpdate[c]; // You create an array of 5 elements for example
bookingupdate[c].bookingID = (long)rdr["ID"]; // Here you access the 5th elements but there are only 4
答案 4 :(得分：0)
数组的零基于索引。
当您创建bookingupdate = new BookingUpdate[c];时，您的上一个索引会c-1。
您无法访问BookingUpdate[c]，因为它不是存在。
让我们说c = 4，这意味着我们定义了一个包含4个元素的数组;
BookingUpdate[0]
BookingUpdate[1]
BookingUpdate[2]
BookingUpdate[3]
BookingUpdate[c]等于BookingUpdate[4]，没有这样的索引。
来自MSDN页;
数组是零索引的：具有 n 元素的数组从 0 索引到 的 N-1
答案 5 :(得分：0)
问题与数组的大小有关;
for (int c = 0; c < count; c++)
{
bookingupdate = new BookingUpdate[c];
bookingupdate[c].bookingID = (long)rdr["ID"];
在前面的代码中，您首先要创建一个大小为0的数组（bookingupdate）;然后你试图插入一个项目。即使你以某种方式设法跳过第一个，它也会再次失败。只需将这些行更新为以下内容;
bookingupdate = new BookingUpdate[count];
for (int c = 0; c < count; c++)
{
bookingupdate[c].bookingID = (long)rdr["ID"];
答案 6 :(得分：0)
for (int c = 0; c < count; c++)
{
bookingupdate = new BookingUpdate[c];
错误是此for循环的第一次迭代，其中c为零。即，您正在尝试创建一个长度为零的数组。 bookingupdate = new BookingUpdate [0];
答案 7 :(得分：0)
在调用之前，您已经初始化了一个数组，但不是该类本身。你的初始化也是错误的
count = dt.Rows.Count;
bookingupdate = new BookingUpdate[count];
for (int c = 0; c < count; c++)
{
bu = new BookingUpdate();
bu.bookingID = (long)rdr["ID"]; // <---- Error is here
bu.fullUserName = rdr["VERANSTALTER"].ToString();
bu.newStart = (DateTime)rdr["VON"];
bu.newStart = (DateTime)rdr["BIS"];
bu.newSubject = rdr["THEMA"].ToString();
bu.newlocation = rdr["BEZEICHNUNG"].ToString();
if (rdr["STORNO"].ToString() != null)
{
bu.deleted = true;
}
else
{
bu.deleted = false;
}
bookingupdate[c] = bu;
}
答案 8 :(得分：0)
使用此代码
public BookingUpdate[] getBookingUpdates(string token)
{
String command = "SELECT b.ID,b.VERANSTALTER, rr.VON ,rr.BIS, b.THEMA, b.STORNO, ra.BEZEICHNUNG from BUCHUNG b JOIN RESERVIERUNGRAUM rr on rr.BUCHUNG_ID = b.ID JOIN RAUM ra on ra.ID = rr.RAUM_ID WHERE b.UPDATE_DATE BETWEEN DATEADD (DAY , -20 , getdate()) AND getdate() AND b.BOOKVERNR = 0";
BookingUpdate[] bookingupdate;
SqlConnection connection = new SqlConnection(GetConnectionString());
connection.Open();
try
{
SqlCommand cmd = new SqlCommand(command, connection);
SqlDataReader rdr = null;
int count = 0;
rdr = cmd.ExecuteReader();
while (rdr.Read())
{
DataTable dt = new DataTable();
dt.Load(rdr);
count = dt.Rows.Count;
bookingupdate = new BookingUpdate[count];
for (int c = 0; c < count; c++)
{
bookingupdate[c].bookingID = (long)rdr["ID"]; // <---- Error is here
bookingupdate[c].fullUserName = rdr["VERANSTALTER"].ToString();
bookingupdate[c].newStart = (DateTime)rdr["VON"];
bookingupdate[c].newStart = (DateTime)rdr["BIS"];
bookingupdate[c].newSubject = rdr["THEMA"].ToString();
bookingupdate[c].newlocation = rdr["BEZEICHNUNG"].ToString();
if (rdr["STORNO"].ToString() != null)
{
bookingupdate[c].deleted = true;
}
else
{
bookingupdate[c].deleted = false;
}
}
}
}
catch (Exception ex)
{
log.Error(ex.Message + "\n\rStackTrace:\n\r" + ex.StackTrace);
}
finally
{
connection.Close();
}
return bookingupdate;
}