How to add results of two select commands in same query

Question

I currently have two select commands as per below. What I would like to do is to add the results together in the SQL query rather than the variables in code.

select sum(hours) from resource; select sum(hours) from projects-time; 

Is it possible to have both in the same SQL and output a sum of both results?

Answer 1

Yes. It is possible :D

SELECT  SUM(totalHours) totalHours FROM         (              select sum(hours) totalHours from resource             UNION ALL             select sum(hours) totalHours from projects-time         ) s 

As a sidenote, the tablename projects-time must be delimited to avoid syntax error. Delimiter symbols vary on RDBMS you are using.

Answer 2

Something simple like this can be done using subqueries in the select clause:

select ((select sum(hours) from resource) +         (select sum(hours) from projects-time)        ) as totalHours 

For such a simple query as this, such a subselect is reasonable.

In some databases, you might have to add from dual for the query to compile.

If you want to output each individually:

select (select sum(hours) from resource) as ResourceHours,        (select sum(hours) from projects-time) as ProjectHours 

If you want both and the sum, a subquery is handy:

select ResourceHours, ProjectHours, (ResourceHours+ProjecctHours) as TotalHours from (select (select sum(hours) from resource) as ResourceHours,              (select sum(hours) from projects-time) as ProjectHours      ) t