Re: Combining two queries

The INNER JOIN to itself with a count turns out to have a lower cost query
plan than the INTERSECT approach. On the ROW approach, it also seems to
take longer than the simple EXISTS query. But I suppose I can put both of
those into CTEs for convenience. I guess I was just hoping there was a
lower cost approach than what I was already doing.

On Thu, Dec 18, 2014 at 2:07 PM, David Johnston <david(dot)g(dot)johnston(at)gmail(dot)com>
wrote:
>
> On Thu, Dec 18, 2014 at 3:02 PM, Robert DiFalco <robert(dot)difalco(at)gmail(dot)com>
> wrote:
>
>> Is the intersect any better than what I originally showed? On the ROW
>> approach, I'm not sure where the context for that is coming from since it
>> may not be in the intersection. Consider n1 and n2 are NOT friends but they
>> have >0 mutual friends between them.
>>
>>
> ​The INTERSECT is a lot more direct about finding mutual friends. The
> ROW() = ROW() piece is independent of the mutual friends question - it
> should be put in a WHERE clause and you can test whether a row is returned
> which, if one is, means the two people are friends.​
>
> ​"One Query" does not mean you need to do everything​ all-at-once. I
> suggest you make use of CTEs (WITH) subqueries for each distinct
> calculation you need then join all of the CTE items together in a final
> query the outputs the data in the format desired.
>
> David J.
>
>