Simplified example of a problem I am trying to solve:
EDIT - With PK
sqlfiddle: http://sqlfiddle.com/#!2/7be5d/1
---
I have two tables:
People
--------
| Name |
--------
| Mike |
| Jim |
| Fred |
--------
HasBanana
------------------------
| Name | Has_a_banana |
------------------------
| Mike | N |
| Mike | N |
| Mike | N |
| Mike | N |
| Mike | Y |
| Mike | N |
| Jim | N |
| Jim | N |
| Jim | Y |
| Jim | N |
| Jim | N |
| Fred | N |
| Fred | N |
| Fred | N |
| Fred | N |
| Fred | N |
| Fred | N |
------------------------
And a query:
select * from People
left join HasBanana on HasBanana.name = People.name;
This produces a table exactly the same as the HasBanana table above. What I would like to produce is a table grouped by People.name and showing Y if the person has ever been marked as having a banana.
So something like this:
HadBanana
------------------------
| Name | Had_a_banana |
------------------------
| Mike | Y |
| Jim | Y |
| Fred | N |
------------------------
I know I can use the following to group by name
group by people.name;
but having issues doing the logic to say for each name if has_a_banana has ever been Y then set had_a_banana to Y.
select
p.name
, case when x.name is null then 'N' else 'Y' end as had_a_banana
from people p
left outer join
(
select
name
from bananas
where has_a_banana = 'Y'
group by name
) x
on x.name = p.name
group by p.name, x.name
I've checked this using your SQLFiddle link, although your Fiddle data does not match your question, so I get:
Fred N
Jim Y
Mike N
(which seems to match your Fiddle data).
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