[vox-tech] SQL help - unions

[David Hummel]

On Tue, Jul 20, 2004 at 04:44:47PM -0700, Peter Jay Salzman wrote:
> 
> 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;

This should do the trick:

SELECT SSN from [Fall 2003] where race = 0;
UNION
SELECT SSN from [Spring 2004] where race = 0;