通过 CTE 或子查询与其下属更新记录

Question

假设我有一个包含以下列的表：

Employees 表

employeeID int
employeeName varchar(50)
managerID int
totalOrganization int

managerID 引用了 employeeID。目前所有记录的totalOrganization 均为0。

我想将每行的 TotalOrganization 更新为其下的员工总数。

因此，使用以下记录：

employeeID     employeeName     managerID     totalOrganization
1              John Cruz        NULL          0
2              Mark Russell     1             0
3              Alice Johnson    1             0
4              Juan Valdez      3             0

查询应将totalOrganizations 更新为：

employeeID     employeeName     managerID     totalOrganization
1              John Cruz        NULL          3
2              Mark Russell     1             0
3              Alice Johnson    1             1
4              Juan Valdez      3             0

我知道我可以获得一些组织。使用以下 CTE 的图表：

WITH OrgChart (employeeID, employeeName,managerID,level)
AS (
    SELECT employeeID,employeeName,0 as managerID,0 AS Level
    FROM Employees
    WHERE managerID IS NULL
    UNION ALL
    SELECT Employees.employeeID,Employees.employeeName,Employees.managerID,Level + 1
    FROM Employees INNER JOIN
    OrgChart ON Employees.managerID = OrgChart.employeeID
   )
SELECT employeeID,employeeName,managerID, level
FROM OrgChart;

是否有任何方法可以使用存储过程来更新员工表，而不是在 SQL 之外构建一些例程来解析数据？

Answer 1

经过几个小时的实验，我得出了以下结论。它给出了所需的结果。有人看到改进的方法吗？

CREATE TABLE #totalOrganization (employeeID int,managerID int,level int);
CREATE TABLE #countedOrganization (employeeID int,managerID int,orgCount int,level int);


WITH OrgChart (employeeID,managerID,level) 
AS ( 
    SELECT employeeID,0 as managerID,0 AS Level 
    FROM Emp
    WHERE managerID IS NULL 
    UNION ALL 
    SELECT Emp.employeeID,Emp.managerID,Level + 1 
    FROM Emp 
        INNER JOIN OrgChart  
            ON Emp.managerID = OrgChart.employeeID 
   )
INSERT INTO
    #totalOrganization
    SELECT 
        employeeID,managerID,level
    FROM
        OrgChart;

DECLARE @maxLevel int
SELECT 
    @maxLevel = MAX(level)
FROM
    #totalOrganization;

WHILE (@maxLevel > -1)
    BEGIN
        INSERT INTO
            #countedOrganization
            SELECT
                upline.employeeID,upline.managerID,SUM(CONVERT(INT,CASE WHEN downline.orgCount IS NULL THEN 0 ELSE downline.orgCount END)) + CONVERT(INT,CASE WHEN COUNT(downline.employeeID) IS NULL THEN 0 ELSE COUNT(downline.employeeID) END),upline.level
            FROM
                #totalOrganization AS upline LEFT OUTER JOIN
                #countedOrganization AS downline ON downline.managerID=upline.employeeID
            WHERE
                upline.level = @maxLevel
            GROUP BY
                upline.employeeID,upline.managerID,upline.level

        SET @maxLevel = @maxLevel - 1
    END

UPDATE
    Emp
SET
    totalOrg= CONVERT(INT,CASE WHEN orgCount IS NULL THEN 0 ELSE orgCount END)
FROM
    #countedOrganization INNER JOIN
    Emp ON #countedOrganization.employeeID=Emp.employeeID

Answer 2

您可以添加另一个 CTE 来确定员工数量，然后在 Update 语句中使用它：

WITH OrgChart (employeeID, employeeName,managerID,level)
AS (
    SELECT employeeID,employeeName,0 as managerID,0 AS Level
    FROM Employees
    WHERE managerID IS NULL
    UNION ALL
    SELECT Employees.employeeID,Employees.employeeName,Employees.managerID,Level + 1
    FROM Employees 
        INNER JOIN OrgChart 
            ON Employees.managerID = OrgChart.employeeID
   )
   , SubordinateCount As
   (
   Select ManagerId, Count(*) As Total
   From OrgChart
   Group By ManagerId
   )
Update Employees
Set TotalOrganization = SubordinateCount.Total
FROM SubordinateCount
    Join Employees As E
        On E.employeeId = SubordinateCount.ManagerId

ADDITION

规范中的更改是您需要所有下级员工的数量。做到这一点的诀窍是为员工创建一条通往每位经理的路径。因此，首先这是我的测试数据：

Insert Employees(EmployeeId, Name, ManagerId) Values(1, 'Alice', Null)
Insert Employees(EmployeeId, Name, ManagerId) Values(2, 'Bob', 1)
Insert Employees(EmployeeId, Name, ManagerId) Values(3, 'Charlie', 1)
Insert Employees(EmployeeId, Name, ManagerId) Values(4, 'Dan', 3)
Insert Employees(EmployeeId, Name, ManagerId) Values(5, 'Ellen', 3)
Insert Employees(EmployeeId, Name, ManagerId) Values(6, 'Fred', 5)
Insert Employees(EmployeeId, Name, ManagerId) Values(7, 'Gale', 6)
Insert Employees(EmployeeId, Name, ManagerId) Values(8, 'Harry', 6)

因此，首先我们编写一个查询，为我们提供通往其经理的路径：

With 
    OrgChart As
    (
    Select E.EmployeeId, E.Name, Null As ManagerId, 0 AS Level
        , Cast( '/' + Cast(E.EmployeeId As varchar(10)) + '/' As varchar(100) ) As Path
    From dbo.Employees As E
    Where E.ManagerId Is Null
    Union All
    Select E.EmployeeID, E.Name, E.ManagerID, Level + 1
        , Cast( OrgChart.Path + Cast(E.EmployeeId As varchar(10)) + '/' As varchar(100))
    From dbo.Employees As E
        Join OrgChart 
            On OrgChart.EmployeeId = E.ManagerID
   )
Select *
From OrgChart 

生成：

    EmployeeId  Name    ManagerId   Level   Path
    1           Alice       NULL        0       /1/
    2           Bob         1           1       /1/2/
    3           Charlie     1           1       /1/3/
    4           Dan         3           2       /1/3/4/
    5           Ellen       3           2       /1/3/5/
    6           Fred        5           3       /1/3/5/6/
    7           Gale        6           4       /1/3/5/6/7/
    8           Harry       6           4       /1/3/5/6/8/

现在我们只需计算给定员工存在于某人路径中的实例：

With 
    OrgChart As
    (
    Select E.EmployeeId, E.Name, Null As ManagerId, 0 AS Level
        , Cast( '/' + Cast(E.EmployeeId As varchar(10)) + '/' As varchar(100) ) As Path
    From dbo.Employees As E
    Where E.ManagerId Is Null
    Union All
    Select E.EmployeeID, E.Name, E.ManagerID, Level + 1
        , Cast( OrgChart.Path + Cast(E.EmployeeId As varchar(10)) + '/' As varchar(100))
    From dbo.Employees As E
        Join OrgChart 
            On OrgChart.EmployeeId = E.ManagerID
   )
    , OrgCounts As
    (
    Select O.EmployeeId, O.Name, O.ManagerId, O.Level, O.Path
        , (Select Count(*)
            From OrgChart As O1
            Where O1.Path Like '%/' + Cast(E.EmployeeId As varchar(10)) + '/%') - 1 As SubordinateTotal
    From Employees As E
        Join OrgChart As O
            On O.EmployeeId = E.EmployeeId
    )
Select O.EmployeeId, O.Name, O.ManagerId, O.Level, O.Path, O.SubordinateTotal
From OrgCounts

我从总数中减去 1排除当前员工。现在我们已经找到了一个可以提供正确结果的查询，我们可以轻松地使用它来进行更新：

With 
    OrgChart As
    (
    Select E.EmployeeId, E.Name, Null As ManagerId, 0 AS Level
        , Cast( '/' + Cast(E.EmployeeId As varchar(10)) + '/' As varchar(100) ) As Path
    From dbo.Employees As E
    Where E.ManagerId Is Null
    Union All
    Select E.EmployeeID, E.Name, E.ManagerID, Level + 1
        , Cast( OrgChart.Path + Cast(E.EmployeeId As varchar(10)) + '/' As varchar(100))
    From dbo.Employees As E
        Join OrgChart 
            On OrgChart.EmployeeId = E.ManagerID
   )
    , OrgCounts As
    (
    Select O.EmployeeId, O.Name, O.ManagerId, O.Level, O.Path
        , (Select Count(*)
            From OrgChart As O1
            Where O1.Path Like '%/' + Cast(E.EmployeeId As varchar(10)) + '/%') - 1 As SubordinateTotal
    From Employees As E
        Join OrgChart As O
            On O.EmployeeId = E.EmployeeId
    )
Update Employees
Set TotalOrganization = O.SubordinateTotal
From OrgCounts As O
    Join dbo.Employees As E
        On E.EmployeeId = O.EmployeeId

Answer 3

这（当然）可以在存储过程中完成。然而，它看起来很像不能用单个（CTE）语句来完成，因为您无法对给定员工的下属+他们的所有下属进行求和（即计算给定项目下的所有后代）层次结构），按照此错误消息：

GROUP BY, HAVING, or aggregate functions are not allowed in the recursive part of a recursive common table expression 'Subordinates'.

因此，必须编写在 SQL 之外编写的例程（从层次结构的最低“级别”开始，计算所有员工下属，在迭代层次结构时重复）在 SQL 中。