Question

我已经成功模拟了SQL Server 2008中的Oracle CONNECT BY语句，方法是按照前面的2个答案here和here进行调整，以获得我需要的结果。但是我如何在LINQ中执行此操作？

以下是我使用虚拟数据库进行操作的示例：

CREATE TABLE Employee(
 EmployeeID INT IDENTITY(1,1) PRIMARY KEY,
 Department INT NOT NULL,
 EmployeeName VARCHAR(40) NOT NULL,
 PeckingOrder INT NOT NULL,
 HigherDepartment INT NULL)

INSERT INTO Employee (Department,EmployeeName,PeckingOrder,HigherDepartment)
VALUES (1,'Bart',1,NULL),(2,'Homer',1,1),(2,'Marge',2,NULL),
       (3,'Lisa',1,2),(3,'Maggie',2,2),(3,'Santas Helper',3,1)

EmployeeID Department EmployeeName PeckingOrder HigherDepartment
    1            1     Bart            1             NULL
    2            2     Homer           1              1 
    3            2     Marge           2             NULL
    4            3     Lisa            1              2
    5            3     Maggie          2              2
    6            3     Santas Helper   3              1

这是用于返回heirachy的SQL：

WITH n(level, PeckingOrder, Department, EmployeeName, HigherDepartment) AS 
    (SELECT 1, PeckingOrder, Department, EmployeeName, HigherDepartment
    FROM Test.dbo.Employee
    WHERE Department = 3
        UNION ALL
   SELECT n.level + 1, nplus1.PeckingOrder, nplus1.Department, nplus1.EmployeeName, nplus1.HigherDepartment 
   FROM Test.dbo.Employee as nplus1
   JOIN n ON n.HigherDepartment = nplus1.Department)
SELECT MAX(level) AS level, PeckingOrder, Department, EmployeeName, HigherDepartment   
FROM n
GROUP BY PeckingOrder, Department, EmployeeName, HigherDepartment
ORDER BY MAX(level) DESC, PeckingOrder ASC

level PeckingOrder Department EmployeeName HigherDepartment
  3         1           1           Bart             NULL
  2         1           2           Homer              1
  2         2           2           Marge             NULL
  1         1           3           Lisa               2
  1         2           3           Maggie             2
  1         3           3           Santas Helper      1

Answer 1

您可以使用ExecuteQuery：

class YourRow
{
    public int level {get; set;}
    public int PeckingOrder {get; set;}
    ...
}

using (var db = new LinqDataContext())
{
    var list = db.ExecuteQuery<YourRow>(
@"
WITH n(level, PeckingOrder, Department, EmployeeName, HigherDepartment) AS 
    (SELECT 1, PeckingOrder, Department, EmployeeName, HigherDepartment
...
";
}

或者更好的是，创建一个包含查询的视图，并使用LINQ从视图中读取。

LINQ中的SQL Server版本的Oracle CONNECT BY显示层次结构

1 个答案: