SQL Server - need assistance with sum and case statements - sql-server

Question

I'm using SQL Server 2005. I'm looking to add up the columns (AM, Midday, Evening) to see which ones contains the value "YES" and then take that total and multiply it by the rate for each row for a client.
Here is the query I have so far:
Select
Sum(Case When morning = 'yes' Then 1 Else 0 End) am_total,
Sum(Case When midday = 'yes' Then 1 Else 0 End) midday_total
From services
where client_id = 24
with the following output
am_total midday_total
45 49
When I introduce the rate variable, my query starts telling me I need the group_by clause and I don't think I'm ready for that since I still need to add the am_total and the midday_total together first and then multiply that by the rate.
Ultimately, all I'm looking for is the grand total.

Answer 1

If I understand your question, maybe this is what you need
declare #rate int
set #rate = 2 /*what ever rate is */
select am_total * #rate as am, midday_total * #rate as midday
from (
Select
Sum(Case When morning = 'yes' Then 1 Else 0 End) am_total,
Sum(Case When midday = 'yes' Then 1 Else 0 End) midday_total
From services
where client_id = 24
)
You can also join another table and use its columns in calculation
Select
Sum(Case When morning = 'yes' Then 1 * u.rate Else 0 End) am_total,
Sum(Case When midday = 'yes' Then 1 * u.rate Else 0 End) midday_total
From services srv inner join users u on services.id = u.service_id -- assuming this is relation
pay attention on u.rate above