[vox-tech] SQL help - unions

[Michael J Wenk]

On Tue, Jul 20, 2004 at 04:44:47PM -0700, Peter Jay Salzman wrote:
> Total newbie here.  I know less about SQL than I do about xkb.   ;-)
> 
> I have two tables, with the same structure.  Call them [Fall 2003] and
> [Spring 2004].  They each hold data about enrolled students.  One of the
> fields of these tables is SSN (social security number).
> 
> I can get an unduplicated headcount for the academic year with:
> 
>    SELECT SSN from [Fall 2003]
>    UNION
>    SELECT SSN from [Spring 2004];
> 
> There's also a field called "race".  If the race field is 0, the student
> is African American.
> 
> How would I modify the above SQL statement to list the unduplicated
> headcount of all African Americans?  I would like to do something like:
> 
>    SELECT SSN from [Fall 2003]
>    UNION
>    SELECT SSN from [Spring 2004]
>    and race == 1;
> 
> but of course that doesn't work.  :)
> 
> Thanks!
> Pete
>


If memory serves, you want: 

SELECT distinct SSN from Fall_2003, Spring_2004 where race = 0

(That will only work if race is a column in both tables)