如何在LINQ中编写自联接

本文介绍了如何在LINQ中编写自联接的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 我们如何在LINQ中编写自联接？我试过这个： 来自 coa GL0_ChartOfAccounts join c 在coa.MainAccount上的GL0_ChartOfAccounts等于c.ControlAccount into cs 来自 ca cs.DefaultIfEmpty（） 选择 new { MainAccount = coa.MainAccount， Title = coa.Title， ControlLevel = coa.ControlLevel， ControlAccount = coa.ControlAccount， ControlTitle = ca.Title } 不幸的是，这给了一个匿名类型错误。 为了澄清这一点，假设有三列： MainAccount 标题 ParentAccount 现在我想得到帐户的名称或名称，而不是ParentAccount（int）我该怎么办？在LINQ中使用这个吗？解决方案 var q =（来自coocha in Glochartofaccount 加入c in glochartofaccount on coamainaccount equals c controlaccount 选择新的 { MainAccount = coa.MainAccount， Title = coa.Title， ControlLevel = coa.ControlLevel， ControlAccount = coa.ControlAccount， ControlTitle = ca.Title ）.FirstOrDefault（）; 尝试使用此示例.. 列表< employee> emp = new 列表< employee>（）; emp.Add（ new Employee（） { EmpID = 1 ， EmpName = a， City = Pune， ManagerID = 11 }）; emp.Add（ new Employee（） { EmpID = 2 ， EmpName = b， City = mumbai， ManagerID = 12 }）; emp.Add（ new Employee（） { EmpID = 3 ， EmpName = c， City = Pune， ManagerID = 2 }）; emp.Add（ new Employee（） { EmpID = 4 ， EmpName = d， City = 德里， ManagerID = 14 }）; // ---- Linq查询 var q =（来自员工 emp join employee2 在 emp中，employee.EmpID等于employee2.ManagerID 选择员工）.FirstOrDefault（）; < / 员工 > < / 员工 > How do we write self join in LINQ? I have tried this:from coa in GL0_ChartOfAccounts join c in GL0_ChartOfAccounts on coa.MainAccount equals c.ControlAccount into cs from ca in cs.DefaultIfEmpty() select new { MainAccount = coa.MainAccount,Title = coa.Title,ControlLevel = coa.ControlLevel,ControlAccount = coa.ControlAccount,ControlTitle = ca.Title}Unfortunately, this gives an anonymous type error.To clarify this, suppose there are three columns:MainAccountTitleParentAccountNow I want to get title or name of account instead of ParentAccount(int) how should I write this in LINQ? 解决方案 var q = (from coa in Glochartofaccount join c in Glochartofaccount on coamainaccount equals c controlaccount select new{MainAccount = coa.MainAccount,Title = coa.Title,ControlLevel = coa.ControlLevel,ControlAccount = coa.ControlAccount,ControlTitle = ca.Title).FirstOrDefault();try by using this sample..List<employee> emp = new List<employee>();emp.Add(new Employee(){ EmpID = 1, EmpName = "a", City = "Pune", ManagerID = 11});emp.Add(new Employee(){ EmpID = 2, EmpName = "b", City = "mumbai", ManagerID = 12});emp.Add(new Employee(){ EmpID = 3, EmpName = "c", City = "Pune", ManagerID = 2});emp.Add(new Employee(){ EmpID = 4, EmpName = "d", City = "Delhi", ManagerID = 14});//----Linq queryvar q = (from employee in emp join employee2 in emp on employee.EmpID equals employee2.ManagerID select employee).FirstOrDefault();</employee></employee> 这篇关于如何在LINQ中编写自联接的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！