Question

I having trouble in my sql query .Please see my
example

As u see, the inventory Report is the parent for the stock alert and stock movement report.

Now i got a question. How can i select the parent’s read access to become ‘Y’ when there has any child record which has ‘Y’ read_access? On the other hand , if there aren’t any existing child record which has ‘Y’, the parent read_acess will become ‘N’

Sorry for my bad english. Please help

Answer 1

This should work:

SELECT ISNULL(CHILDREN_TABLE.READ_ACCESS, PARENT_TABLE.READ_ACCESS) AS READ_ACCESS
FROM TABLE AS PARENT_TABLE
    LEFT JOIN TABLE AS CHILDREN_TABLE
        ON CHILDREN_TABLE.Parent = PARENT_TABLE.Child

It will give you duplicates, though (2 rows for Inventory Report, one for Stock Alert Report and one for Stock Movement Report) You can resolve this with a SELECT DISTINCT …

OR, I believe adding a GROUP BY in the children table will solve the duplicate:

SELECT ISNULL(CHILDREN_TABLE.READ_ACCESS, PARENT_TABLE.READ_ACCESS) AS READ_ACCESS
FROM TABLE AS PARENT_TABLE
    LEFT JOIN (SELECT Parent, READ_ACCESS FROM TABLE GROUP BY Parent) AS CHILDREN_TABLE
        ON CHILDREN_TABLE.Parent = PARENT_TABLE.Child

Now, you will still get a duplicate if there is a child that has READ_ACCESS of Y and another that has READ_ACCESS of N. However, this sounds like something that would need to be discussed with your business rules anyway.