Tableau - How check if a value equals a value from another row and column - tableau-api

Question

I have the following table:
+------------+--------------+---------+---------+---------+
| Category | Subcategory |FruitName| Date1 | Date2 |
+------------+--------------+---------+---------+---------+
| A | 1 | Foo | 2011 | 2017 |
| | +---------+---------+---------+
| | |Pineapple| 2011 | 2013 |
| | +---------+---------+---------+
| | | Apple | 2017 | 2018 |
| +--------------+---------+---------+---------+
| | 2 | Peach | 2014 | 2015 |
| | +---------+---------+---------+
| | | Orange | 2015 | 2018 |
| | +---------+---------+---------+
| | | Banana | 2009 | 2013 |
+------------+--------------+---------+---------+---------+
I'd like to display the fruit names where Date1 from one row == Date2 from another row, but only if they are equals within the same Subcategory. In the table above, this filter should retrieve the rows based on those criterias:
And the final table would look like this:
+------------+--------------+---------+---------+---------+
| Category | Subcategory |FruitName| Date1 | Date2 |
+------------+--------------+---------+---------+---------+
| A | 1 | Foo | 2011 | 2017 |
| | +---------+---------+---------+
| | | Apple | 2017 | 2018 |
| +--------------+---------+---------+---------+
| | 2 | Peach | 2014 | 2015 |
| | +---------+---------+---------+
| | | Orange | 2015 | 2018 |
+------------+--------------+---------+---------+---------+
How can I possibly achieve this?

Answer 1

Your logic provided doesnot match with the output provided. If you are after the output, your logic should be:
SELECT f1.* from fruits f1 JOIN fruits f2
ON f1.Subcategory=f2.Subcategory
WHERE f1.Date1=f2.Date2 OR f1.Date2 = f2.Date1;
If your data source supports custom SQL, you can straight away use the above query. If not you can still achieve it in Tableau using a Full Outer Join and a calculated Field.(Tableau doesn't support OR condition in Joins.)
Create a self full outerjoin with the following criteria
Create a calculation called 'FILTER' as below
Apply a datasource filter to keep only 'FILTER' = True
Hide Fields from the rightside connection and you will have the required output.