Group by in a new column

Hi everyone!

I want to add a new column with the family of the items in a table.

There is any formula in which you give a list of values and if the value is matched then you make an action.

Something like:

IF  id_item IN (1,2,4) THEN "Family_1"

ELSE IF id_item IN (3,5) THEN "Family_2"

ELSE "Family_3"

I have this:

ID_item   Name 

------------------

1             ItemA

2             ItemB

3             ItemC

4             ItemD

5             ItemE

6             ItemF

And I want this:

ID_item   Name    Family

-----------------------------

1             ItemA    Family_1

2             ItemB    Family_1

3             ItemC    Family_2

4             ItemD    Family_1

5             ItemE     Family_2

6             ItemF     Family_3

Thanks!