在SQL中循环行并匹配值

感谢您对我的问题的任何帮助！我有一张所有员工的组织结构图，然后是他们主管的专栏。我试图为每个有3年以上工作经验的员工找到组织结构中的第一位主管。因此，如果主管1只有一年的时间，我将需要转到下一个专栏《超级visor 2》，看看他们是否有更多的经验。最后，我想返回一列主管ID[经验丰富的主管栏]

表：组织结构图

   id   |  experience   | supervisor_id_1| supervisor_id_2 | experienced_supervisor
    A   |      2        |     X          |    C            |    X
    C   |      5        |     V          |    D            |    D
    V   |      1        |     M          |    X            |    M
    X   |      3                            
    D   |      8
    M   |      11

我是SQL新手，甚至不确定这是否是最好的方法。但我的想法是：我将使用这个案例来审视每一行员工，并比较他们的主管的经验

SELECT CASE 
  WHEN  experience >=3   THEN   supervisor_id_1 
     ELSE 
       CASE WHEN  experience >=3   THEN   supervisor_id_2
       ELSE 'not found'
     END AS experienced_supervisor
FROM org_chart

问题:

这是解决这个问题的最好办法吗？ 我可以通过将主管id\u 1、主管id\u 2与id匹配来查找主管的价值[经验年数]吗？或者我是否需要创建一个新的专栏主管\u id\u 1\u经验，并通过加入来填补多年的经验？ 我用的是红移

您只需要一个case表达式，但需要大量的联接或子查询。或许

SELECT (CASE WHEN (SELECT oc2.experience >=3 FROM org_chart oc2 WHERE oc2.id = supervisor_id_1) >= 3
             THEN supervisor_id_1 
             WHEN (SELECT oc2.experience >=3 FROM org_chart oc2 WHERE oc2.id = supervisor_id_2) >= 3
             THEN supervisor_id_2 
             . . .
        END) AS experienced_supervisor
FROM org_chart oc

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经过大量的尝试和错误，这是解决我问题的结果。在这种情况下，我使用的是红移

-- Use common table expression to find job level for each supervisor from reporting levels 8 to 2
WITH cte1 AS
(
SELECT B.id as employee
      ,B.experience as employee_experience
      ,B.supervisor_id_1 as manager_1
      ,A.experience as supervisor_1_experience
      FROM org_chart
      INNER JOIN org_chart B ON B.supervisor_id_1 = A.id
),
cte2 AS
(
SELECT B.id as employee2
      ,B.experience as employee_experience
      ,B.supervisor_id_2 as manager_2
      ,A.experience as supervisor_2_experience
      FROM org_chart
      INNER JOIN org_chart B ON B.supervisor_id_2 = A.id
),
........-- Write as many statements as I have columns with reporting levels
-- Join all tables above
cte3 AS
(
SELECT employee
       ,employee_experience
       ,manager_1
       ,supervisor_1_experience
       ,manager_2
       ,supervisor_2_experience
FROM cte1
JOIN cte2 ON cte2.employee2 = cte1.employee
....... -- Write as many statements as I have columns with reporting levels
)
-- Run through every row and evaluate if each supervisor has more than 3 years of experience 
SELECT *
,CASE
WHEN cte3.supervisor_1_experience >= 3 THEN cte3.manager_1
WHEN cte3.supervisor_1_experience < 3
          AND cte3.supervisor_2_experience >=3
          THEN cte3.manager_2
........ -- Write as many statements as I have columns with reporting levels
END experienced_supervisor
FROM cte3

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用您正在使用的数据库标记您的问题。