Exclude user list(s) from list of members (union?)

Your guidance is really appreciated on the following matter.

I am trying to display a list of users (to a user) by eliminating the use开发者_JAVA技巧rs that already exist in other his/her lists.

For example, I want to display all my sites users to a user, minus his blocked list.

I believe I need to use the UNION operator, but have no previous experience in doing so.

would it be something like?

SELECT * FROM myMembers WHERE id='$id'
UNION
SELECT * FROM blocked WHERE id!='$id'
UNION
.
.
.

Just doesn't feel right... My database scheme is:

myMembers
-----------------------
id        username
-----------------------
1              x
2              y
3              z

Blocked
---------------------------------------------------------
id        mem1        mem2
---------------------------------------------------------
1              2              1
2              4              1

mem2 = the user doing the blocking.

SELECT * FROM myMembers WHERE id NOT IN (SELECT * FROM Blocked WHERE mem2!='$userid')

where userid is the id of the user to whom you are displaying the list

How about the following:

SELECT DISTINCT * FROM myMembers 
WHERE id NOT IN (
  SELECT id FROM Blocked 
  WHERE mem2 = '$user_viewing_list'
)