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[英]C# Linq Select from one to many but if in the many one is false dont return
[英]C# LINQ Select Many
我將案例與控件匹配,基本上是案例列表中的記錄,需要具有字符串m_ctrlno
指定的匹配數。
到目前為止我有兩個列表,where子句是正確的,但是我不確定如何使用SelectMany
來獲得匹配1個Case的3個控件。 我決定使用.Take()
函數,但它似乎沒有工作。 當我在var查詢上循環時,我沒有得到3個不同控件的相同情況。
這是代碼:
List<CaseSelection> CurrentCaseList = new List<CaseSelection>();
foreach (CaseSelection CurrentCase in m_casesarraylist)
CurrentCaseList.Add(CurrentCase);
List<ControlSelection> CurrentControlList = new List<ControlSelection>();
foreach (ControlSelection CurrentControlRec in ControlList)
CurrentControlList.Add(CurrentControlRec);
var query = CurrentCaseList.SelectMany(
c => CurrentControlList.Where(o => o.pracid == c.pracid && o.sex == c.sex &&
CaseSelectionList.AgeIsInRange(c.yob, o.yob, m_years)),
(c, o) =>
new { o, c }).Take(m_ctrlno);
在您的代碼中您定義了2個列表CurrentCaseList,CurrentControlList
但未定義CaseSelectionList
。
要獲得匹配一個案例的3個控件,請參閱下面的代碼:
SelectMany
方法選擇TotalDue
小於500.00的所有訂單。
這是代碼:
decimal totalDue = 500.00M;
using (AdventureWorksEntities context = new AdventureWorksEntities())
{
ObjectSet<Contact> contacts = context.Contacts;
ObjectSet<SalesOrderHeader> orders = context.SalesOrderHeaders;
var query =
contacts.SelectMany(
contact => orders.Where(order =>
(contact.ContactID == order.Contact.ContactID)
&& order.TotalDue < totalDue)
.Select(order => new
{
ContactID = contact.ContactID,
LastName = contact.LastName,
FirstName = contact.FirstName,
OrderID = order.SalesOrderID,
Total = order.TotalDue
}));
foreach (var smallOrder in query)
{
Console.WriteLine("Contact ID: {0} Name: {1}, {2} Order ID: {3} Total Due: ${4} ",
smallOrder.ContactID, smallOrder.LastName, smallOrder.FirstName,
smallOrder.OrderID, smallOrder.Total);
}
}
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