Can you help me to write recursive query for two tables? - sql

Question

I need to write recursive query for finding all child nodes in this tables.
For example i need find all child ExecutorTasks for ParentManagerTaskId = 6
ManagerTasks
{
Id,
ParentExecutorTaskId
}
ExecutorTasks
{
Id,
ParentManagerTaskId
}
;WITH query AS
(
SELECT et.Id,et.ParentManagerTaskId,mt.ParentExecutorTaskId
FROM [Planning.ExecutorTasks] et
left outer join [Planning.ManagerTasks] mt on et.ParentManagerTaskId=mt.Id
WHERE mt.Id = 6
UNION ALL
SELECT q.Id, q.ParentManagerTaskId,et.Id
FROM [Planning.ExecutorTasks] et
JOIN query q ON et.Id = q.Id
)
SELECT *
FROM query

Answer 1

Your model is a little misleading since you have 2 tables that are related against each other and you only want to display records from one. This means you have to do 2 joins on the recursive part to get the children of the related entity.
Try with the following:
;WITH Recursion AS
(
-- Anchor
SELECT
ExecutorTaskId = E.Id,
RecursionLevel = 0
FROM
[Planning.ExecutorTasks] AS E
WHERE
E.ParentManagerTaskId = 6
UNION ALL
-- Further childs
SELECT
ExecutorTaskId = E.Id,
RecursionLevel = R.RecursionLevel + 1
FROM
Recursion AS R
INNER JOIN [Planning.ManagerTasks] AS M ON R.ExecutorTaskId = M.ParentExecutorTaskId
INNER JOIN [Planning.ExecutorTasks] AS E ON M.Id = E.ParentManagerTaskId
)
SELECT
R.RecursionLevel,
R.ExecutorTaskId
FROM
Recursion AS R
ORDER BY
R.RecursionLevel,
R.ExecutorTaskId
I can't test if you don't supply example values, expected outcome and table's DDL.