Selecting two values from the same table but under different conditions I want to grab a value from a table into two different columns for different values from the same table. Use this query as an example (notice how the select is on the same table aliased as 2 different tables):

SELECT a.myVal, b.myVal 
FROM MyTable a, MyTable b
WHERE 
  a.otherVal = 100 AND
  b.otherVal = 200 AND
  a.id = b.id


When I run a relatively simple query like this on my dataset, it works - it just takes a long time. Is there a better/smarter way of writing this query?
For readability I would rewrite the query using the more modern join syntax.  This will clearly separate your join conditions from your filters.

select a.myVal,
       b.myVal
  from MyTable a
  join MyTable b on b.id = a.id
where a.OtherVal = 100
  and b.Otherval = 200


For performance, ensure you have proper indexes.  In this limited example, ideally you would have a clustered index on ID and a non-clustered index on OtherVal.

After looking at your query, however, I cannot tell just what it is you are trying to accomplish.