Question

SQL Server 2008

I have a query with several local variables that does some easy math in the result set. When I copy and paste the query to try to save it as a view, it fails telling me there’s incorrect syntax. (in this case it’s near the declare statement of the variables.) If needed I’ll post the query, just wondering if there’s a reason for this to work one way and not the other.

declare @totalpop float,
@totalMales float,
@totalFemales float,
@percentMales float,
@percentFemales float;
select @totalmales=sum(case when sex='m' then 1 else 0 end),
@totalfemales = sum(case when sex='f' then 1 else 0 end),
@totalpop=count(*)

from tblVisits
select @percentmales = round(100 * @totalmales/@totalpop,2),
@percentFemales = round(100*@totalfemales/@totalpop,2)

select @totalmales,@percentmales,@totalfemales, @percentfemales, @totalpop

Answer 1

You don’t need any of the declared variables, you can do this in plain-old sql with a nested select:

SELECT totalmales, round(1e2*totalmales/totalpop, 2) percentmales,
       totalfemales, round(1e2*totalfemales/totalpop, 2) percentfemales,
       totalpop
FROM (SELECT sum(case when sex='m' then 1 else 0 end) totalmales,
             sum(case when sex='f' then 1 else 0 end) totalfemales,
             count(*) totalpop
      FROM tblVisits) innerquery

Which should be usable on most any database that supports views and subselects (which is basically all of them.