retrieve unique entries

[rogerwin7]

Hi,

I have tree tables client, org, desg.
client contain fields name, email
org contain location, email, address
desg contain level, email, digit
i want to select only unique email ids from all the tree tables in a single query.
anybody please help me to build this query

 

[pbaldy]

SELECT EmailField
FROM FirstTable
UNION
SELECT EmailField
FROM SecondTable
UNION
SELECT EmailField
FROM ThirdTable