GROUP BY Create group if at least one value in group meets condition

Question

How to create group if at least one value in group meets condition?

Here is an example of DB table test:

| ID | TYPE | COLOR |
|====|======|=======|
|  1 |    1 |     R |
|  2 |    1 |     B |
|  3 |    1 |     G |
|  4 |    2 |     B |
|  5 |    2 |     G |
|  6 |    3 |     G |

I need to select all TYPE values that have more than one row, and at least one of COLORs is G for that TYPE.

So pseudo-select would look like this:

  select TYPE 
    from test
group by TYPE
  having count(*) > 1
     and count(COLOR = 'G') > 0

Answer 1

With the OP's modified requirement:

select   type
from     test
group by type
having   count(*) > 1 and count(case when color = 'G' then 0 end) > 0
;

Answer 2

count only counts non-null values. A neat trick to wrap both required conditions into one is to count the distinct number of a case expression that returns something for G and something else for any other value:

SELECT   type
FROM     test
GROUP BY type
HAVING   COUNT(DISTINCT CASE color WHEN 'G' THEN 1 ELSE 2 END) = 2