I have successfully simulated an Oracle CONNECT BY statement in SQL Server 2008 by following these 2 previous answers here and here and adjusting to get the results I need. But how do I do this in LINQ?
Here is an example of what I am doing using a dummy database:
CREATE TABLE Employee(
EmployeeID INT IDENTITY(1,1) PRIMARY KEY,
Department INT NOT NULL,
EmployeeName VARCHAR(40) NOT NULL,
Peck开发者_如何转开发ingOrder 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
and this is the SQL used to return the heirachy:
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
You could use 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
...
";
}
Or perhaps better, create a view that contains the query, and use LINQ to read from the view.
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