Re: Union Clause

Mtek wrote:
> Hi,
>
> This is my query:
>
> SELECT SUM(zcom) + SUM(ze) + SUM(zp)
> FROM
>     (SELECT count(DISTINCT(email)) FROM customers_lookup) zcom
>     UNION
>     (SELECT count(DISTINCT(email)) FROM customers_lookup) ze
>     UNION
>     (SELECT count(DISTINCT(email)) zp FROM customers_lookup) zp);
>
> Basically I want to get a count from the three tables where the email
> address appears in ALL THREE tables.  If an email does not exist in
> all three tables, then I do not want it counted.......

Use INTERSECT, not UNION.

Or use a normal inner join...

  select count(distinct a.email)
  from
    customers_lookup a
    inner join customers_lookup_ze b on b.email = a.email
    inner join customers_lookup_prim c on c.email = b.email

--
Peter