加入递归查询

Question

设置

我有以下表格（简化）：

CREATE TABLE Category(
    CategoryId              int           NOT NULL PRIMARY KEY,
    ParentCategoryId        int           NULL,
    Name                    nvarchar(255) NOT NULL,
    FOREIGN KEY (ParentCategoryId) REFERENCES Category(CategoryId) ON UPDATE NO ACTION ON DELETE NO ACTION);

CREATE TABLE TimeSlot(
    TimeSlotId              int           NOT NULL PRIMARY KEY,
    CategoryId              int           NOT NULL,
    FOREIGN KEY (CategoryId) REFERENCES Category(CategoryId) ON UPDATE NO ACTION ON DELETE NO ACTION);

CREATE TABLE PersonTimeSlotAssignment(
    PersonId                int           NOT NULL,
    TimeSlotId              int           NOT NULL,
    PRIMARY KEY (PersonId, TimeSlotId),
    FOREIGN KEY (TimeSlotId) REFERENCES TimeSlot(TimeSlotId) ON UPDATE NO ACTION ON DELETE NO ACTION);

这是一些测试数据：

INSERT INTO Category(CategoryId, ParentCategoryId, Name) VALUES (100, NULL, 'cat 1');
INSERT INTO Category(CategoryId, ParentCategoryId, Name) VALUES (110, 100, 'cat 1.1');
INSERT INTO Category(CategoryId, ParentCategoryId, Name) VALUES (111, 110, 'cat 1.1.1');
INSERT INTO Category(CategoryId, ParentCategoryId, Name) VALUES (120, 100, 'cat 1.2');
INSERT INTO Category(CategoryId, ParentCategoryId, Name) VALUES (200, NULL, 'cat 2');

INSERT INTO TimeSlot(TimeSlotId, CategoryId) VALUES (301, 111);
INSERT INTO TimeSlot(TimeSlotId, CategoryId) VALUES (302, 120);
INSERT INTO TimeSlot(TimeSlotId, CategoryId) VALUES (303, 200);

INSERT INTO PersonTimeSlotAssignment(PersonId, TimeSlotId) VALUES (401, 301);
INSERT INTO PersonTimeSlotAssignment(PersonId, TimeSlotId) VALUES (401, 302);
INSERT INTO PersonTimeSlotAssignment(PersonId, TimeSlotId) VALUES (402, 302);
INSERT INTO PersonTimeSlotAssignment(PersonId, TimeSlotId) VALUES (402, 303);

我能做什么

SELECT ts.TimeSlotId, pc.Name 
    FROM PersonTimeSlotAssignment 
    JOIN TimeSlot AS ts ON PersonTimeSlotAssignment.TimeSlotId = ts.TimeSlotId 
    JOIN Category AS pc ON ts.CategoryId = pc.CategoryId
    WHERE PersonTimeSlotAssignment.PersonId = @PERSON_ID;

这为某个人提供了此人分配到的所有 TimeSlot 的列表以及 TimeSlot 所属的叶类别的名称。例如，对于 ID 为 401 的人，它给出：

TimeSlotId  Name
---------------------
301         cat 1.1.1
302         cat 1.2

通过以下递归查询，我还可以从某个类别中获取所有祖先到根类别：

;WITH Parents AS (
    SELECT * FROM Category 
        WHERE CategoryId=@CATEGORY_ID
        UNION ALL SELECT c.* FROM Category c JOIN Parents p ON p.ParentCategoryId=c.CategoryId
    ) 
    SELECT Name FROM Parents;

例如，对于 ID 为 111 的类别，我得到：

Name
---------
cat 1.1.1
cat 1.1
cat 1

我想做什么

我需要的是一个分配给一个人的 TimeSlot 列表，以及该 TimeSlot 的类别名称，直到根类别。因此对于 ID 为 401 的人，结果应如下所示：

TimeSlotId  Name
---------------------
301         cat 1.1.1
301         cat 1.1
301         cat 1
302         cat 1.2
302         cat 1

我无法弄清楚如何组合上述两个查询以获得预期的结果。

我尝试了什么

我希望这些方面的东西可以起作用：

;WITH Parents AS (
    SELECT * FROM Category 
        WHERE CategoryId=<<'How to get CategoryId for each assigned TimeSlot here?'>>
        UNION ALL SELECT c.* FROM Category c JOIN Parents p ON p.ParentCategoryId=c.CategoryId
    ) 
SELECT ts.TimeSlotId, pc.Name 
    FROM PersonTimeSlotAssignment 
    JOIN TimeSlot AS ts ON PersonTimeSlotAssignment.TimeSlotId = ts.TimeSlotId 
    JOIN Parents AS pc ON <<'How should this look like?'>>
    WHERE PersonTimeSlotAssignment.PersonId = @PERSON_ID;

Answer 1

用户定义函数和cross apply在这种情况下非常有用。

--1. Create function
create function fn_Category(@id int)
returns table
as
return
with tbl as (
--anckor query
select CategoryId, ParentCategoryId,Name, 1 lvl
from Category where CategoryId = @id
union all
--recursive query
select c.CategoryId, c.ParentCategoryId,c.Name, lvl+1
from Category c
inner join tbl on tbl.ParentCategoryId=c.CategoryId--go up the tree
)
select * from tbl
go
--end of function

--2. and now we can use it
declare @PERSON_ID int = 401
SELECT ts.TimeSlotId, pc.Name 
    FROM PersonTimeSlotAssignment 
    JOIN TimeSlot AS ts ON PersonTimeSlotAssignment.TimeSlotId = ts.TimeSlotId 
    --JOIN Category AS pc ON ts.CategoryId = pc.CategoryId
    --use cross apply instead
    cross apply fn_Category(ts.CategoryId) pc 
    WHERE PersonTimeSlotAssignment.PersonId = @PERSON_ID;

Answer 2

这将处理递归类别并根据 PersonId 或 TimeSlotId 提供所有数据：

WITH Categories (PersonId, CategoryId, ParentCategoryId, TimeSlotId, Name, BASE)
AS
(
SELECT PersonId, c.CategoryId, c.ParentCategoryId, pts.TimeSlotId, c.Name, 0 AS BASE
FROM Category c
INNER JOIN TimeSlot ts ON c.CategoryId = ts.CategoryId
INNER JOIN PersonTimeSlotAssignment pts ON ts.TimeSlotId = pts.TimeSlotId
UNION ALL
SELECT PersonId, pc.CategoryId, pc.ParentCategoryId, TimeSlotId, pc.Name, BASE + 1
FROM Category pc
INNER JOIN Categories cs ON cs.ParentCategoryId = pc.CategoryId
)
SELECT * FROM Categories 
WHERE PersonId = 401
--WHERE TimeSlotId = 301

可能有更好的方法来写这个，但会按照你的要求去做，应该让你到达你需要去的地方。 'BASE' 并没有达到其最初的目的，但仍然显示了您的 Person 和 Category 之间的相关性，例如BASE 0 表示该记录中的类别直接分配给该人。所以，我把它留给了那个。谢谢。

Answer 3

希望对你有帮助:)

DECLARE @PersonId INT= 401;

WITH CTE AS
(
SELECT 
    t.*,
    c.CategoryId AS CategoryId_c,
    c.ParentCategoryId as ParentCategoryId_c,
    c.Name AS Name_c,
    c1.CategoryId AS CategoryId_c2,
    c1.ParentCategoryId AS ParentCategoryId_c2,
    c1.Name AS Name_c2,
    c2.CategoryId as CategoryId_c3,
    c2.ParentCategoryId AS ParentCategoryId_c3,
    c2.Name AS Name_c3
FROM 
PersonTimeSlotAssignment p
INNER JOIN TimeSlot t ON t.TimeSlotId=p.TimeSlotId
INNER JOIN Category c ON t.CategoryId=c.CategoryId
LEFT JOIN Category c1 ON c1.CategoryId=c.ParentCategoryId
LEFT JOIN Category c2 ON c2.CategoryId=c1.ParentCategoryId
WHERE p.PersonId=@PersonId
)

SELECT * FROM (
    SELECT TimeSlotId,Name_c  FROM CTE 
    UNION
    SELECT TimeSlotId,Name_c2 FROM CTE 
    UNION
    SELECT TimeSlotId,Name_c3 FROM CTE 
)a WHERE Name_c IS NOT NULL

Answer 4

声明@PersonId int =401;

IF OBJECT_ID('tempdb.dbo.#TimeSlot') 不为空
删除表#TimeSlot

SELECT DISTINCT DENSE_RANK() OVER(ORDER BY t.TimeSlotId ) ID, t.TimeSlotId,c.CategoryId
INTO #TimeSlot
FROM PersonTimeSlotAssignment p
INNER JOIN 时隙 t
ON p.TimeSlotId=t.TimeSlotId
内连接类别 c 开启 c.CategoryId=t.CategoryId
WHERE PersonId=@PersonId

IF OBJECT_ID('tempdb.dbo.#Output') 不为空
删除表#输出
创建表 #Output(timeSlotId INT,CategoryId INT)
声明 @id INT=1 声明 @timeSlotId 为 INT 声明 @CategoryId INT
WHILE（从 #TimeSlot 选择 id，其中 id=@id）不为空
开始
SELECT @timeSlotId=TimeSlotId,@CategoryId=CategoryId FROM #TimeSlot WHERE ID=@id
插入#Output SELECT @timeSlotId,@CategoryId
WHILE( SELECT ParentCategoryId FROM Category WHERE CategoryId=@CategoryId) 不为空
开始
SELECT @CategoryId=ParentCategoryId 从类别 WHERE CategoryId=@CategoryId
插入#Output SELECT @timeSlotId,@CategoryId
结束
设置@id=@id+1
结束

SELECT a.timeSlotId,c.Name FROM #Output a INNER JOIN Category c ON a.CategoryId=c.CategoryId