如何在 SQL 服务器中获取分层 CTE 到父子 MAX 日期

Question

I have following table structure:

--===================================================================
-- Create and populate a table for demonstration purposes only:
--===================================================================

IF OBJECT_ID('tempdb..#BOM') IS NOT NULL DROP TABLE #BOM;
CREATE TABLE #BOM (
    ID INT,
    PartID int,
    ChildPartID int,
    FormulaId INT,
    FormulaDateTime datetime,
);

INSERT INTO #BOM
VALUES 
(   17372   ,   114798  ,   119892  ,   12636   ,'10/17/2021 13:40'),
(   17371   ,   118732  ,   119892  ,   12635   ,'10/17/2021 13:38'),
(   16623   ,   7900    ,   118732  ,   12071   ,'5/3/2021 8:32'),
(   16624   ,   7900    ,   115978  ,   12071   ,'5/3/2021 8:32'),
(   16625   ,   7900    ,   115757  ,   12071   ,'5/3/2021 8:32'),
(   16577   ,   118732  ,   114741  ,   12036   ,'4/24/2021 11:57'),
(   16348   ,   7900    ,   115765  ,   11869   ,'2/28/2021 11:47'),
(   16349   ,   7900    ,   114798  ,   11869   ,'2/28/2021 11:47'),
(   16350   ,   7900    ,   115757  ,   11869   ,'2/28/2021 11:47'),
(   15876   ,   115978  ,   115969  ,   11554   ,'11/2/2020 14:19'),
(   15763   ,   115765  ,   115463  ,   11465   ,'10/4/2020 16:10'),
(   15762   ,   115757  ,   115742  ,   11464   ,'10/4/2020 16:01'),
(   15222   ,   114798  ,   114741  ,   11047   ,'6/15/2020 16:52'),
(   13918   ,   7900    ,   9641    ,   9047    ,'8/28/2019 13:37'),
(   13919   ,   7900    ,   23568   ,   9047    ,'8/28/2019 13:37'),
(   13920   ,   7900    ,   16606   ,   9047    ,'8/28/2019 13:37'),
(   12005   ,   7900    ,   9635    ,   7370    ,'3/1/2019 15:58'),
(   12006   ,   7900    ,   9639    ,   7370    ,'3/1/2019 15:58'),
(   12007   ,   7900    ,   25609   ,   7370    ,'3/1/2019 15:58'),
(   11943   ,   25609   ,   11191   ,   7321    ,'2/19/2019 14:25'),
(   10019   ,   16606   ,   11029   ,   6645    ,'7/28/2018 13:07'),
(   9969    ,   23568   ,   11036   ,   6613    ,'7/21/2018 16:47'),
(   6222    ,   9635    ,   11036   ,   3070    ,'1/20/2018 15:45'),
(   6176    ,   9641    ,   11191   ,   3035    ,'1/14/2018 9:14'),
(   5712    ,   9639    ,   11029   ,   2701    ,'11/18/2017 10:28'),
(   6291    ,   7900    ,   9639    ,   1064    ,'10/2/2017 16:30'),
(   6292    ,   7900    ,   9635    ,   1064    ,'10/2/2017 16:30')

In this table, the product (PartID) is produced from one or more other products (ChildPartIDs) with the manufacturing formula number (formulaID) at the time (FormulaDateTime).

    BOMID    PartId    ChildPartId  FormulaId   FormulaDateTime
     16623    7900      118732       12071       5/3/2021 8:32
     16624    7900      115978       12071       5/3/2021 8:32
     16625    7900      115757       12071       5/3/2021 8:32
     17371    118732    119892       12635       10/17/2021 13:38
     12005    7900      9635         7370        3/1/2019 15:58
       .
       .
       .

For example, a Part like with ID 7900, I want to get a hierarchical structure of formulas and constituent products(ChildPartID) based only on the last registered times of the formula.

  7900
   ├────118732
   │        └──119892
   ├────115978
   │        └──115969
   └────115757
            └──115742

According to this tree and table, to produce 7900 according to the time of the last formula, the formulaID is 12071. Therefore, at the first level, ChildPartIDs 118732, 115978 and 115757 are needed to produce 7900. For the next levels, it should be implemented in the same way. In fact, the condition to terminate is when there is no formula for the childPartID.

Please help me how to implement stored procedure recursively to get this tree structure.

Result, query should return: Result

Answer 1

This query does what you need

WITH bom_rn AS (
    SELECT 
        *,
        RANK() OVER (PARTITION BY partid ORDER BY formuladatetime DESC) AS rn
    FROM #bom
),
product_tree AS (
    SELECT 
        *
    FROM bom_rn
    WHERE partid = 7900 AND rn = 1
    UNION ALL
    SELECT 
        bom_rn.*
    FROM bom_rn
    JOIN product_tree ON bom_rn.partid = product_tree.childpartid AND bom_rn.rn = 1
)
SELECT
    id,
    partid,
    childpartid,
    formulaid,
    formuladatetime
FROM product_tree

Query output

id	partid	childpartid	formulaid	formuladatetime
16623	7900	118732	12071	2021-05-03 08:32:00.000
16624	7900	115978	12071	2021-05-03 08:32:00.000
16625	7900	115757	12071	2021-05-03 08:32:00.000
15762	115757	115742	11464	2020-10-04 16:01:00.000
15876	115978	115969	11554	2020-11-02 14:19:00.000
17371	118732	119892	12635	2021-10-17 13:38:00.000

You can check a working demo here