Linq-2-SQL左外部联接在C#中 [英] Linq-2-SQL Left Outer Join in C#

问题描述

此SQL查询的linq-2-sql语法是什么?

What would be the linq-2-sql syntax for this SQL Query:

SELECT emp.id, Name, Count(t.id) as CNT 
FROM employee emp 
LEFT JOIN taskAssignment t 
on emp.id = t.FKEmployeeID GROUP BY emp.id, Name

表是这样的:

推荐答案

这是答案

var lst = from emp in Employeetables
join task in TaskAssignmentTables
    on  emp.EmployeeId equals task.FKEmployeeId into j 
    from result in j.DefaultIfEmpty()
    group result by new { emp.EmployeeId, emp.Name }  into groupResult
select new
{
    EmployeeId = groupResult.Key.EmployeeId,
    Name = groupResult.Key.Name,
    Count = groupResult.Count(r => r.FKEmployeeId != null)
};

这将返回与与此相关的 SQL 问题相同的答案

This returns the same answer as your SQL question related to this SQL Left outer join question. I developed this simply using LinqPad

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