text: Q:
  
  Query that will match a non-unique id if there is data in two separate columns across multiple rows
  
  I'm stuck trying to figure out how to extract data from a single table. What I need a query that will match an id (non-unique) if there is data in two separate columns across multiple rows. Here is an example of the data.
  +---------+---------------+-----------+
  |     id  |  Drivers      | Brands    |
  +---------+---------------+-----------+
  |    1    |               |  Brands   |
  |    2    |   Drivers     |           | 
  |    3    |   Drivers     |           | 
  |    1    |   Drivers     |           | 
  |    4    |               | Brands    | 
  |    2    |   Drivers     |           | 
  |    3    |               | Brands    | 
  |    4    |               | Brands    | 
  +---------+---------------+-----------+
  
  Id 1 and 3 are the only rows that contain values in both Drivers and Brands. This is the data I need.
  Few things about the data:
  
  There will never be a row with both Drivers and Brands.
  Its possible an id will have multiple rows with just Driver or just Brands (cant use count to determine a match).
  
  A:
  
  You can do a GROUP BY. Use the HAVING clause to return ID's that have both driver and brand values:
  select id
  from tablename
  group by id
  having count(drivers) > 0 and count(brands) > 0
  
  Alternatively, use INTERSECT:
  select id from tablename where drivers is not null
  intersect
  select id from tablename where brands is not null
  
  INTERSECT returns the two selects' common rows, and removes duplicates.
  
  