SQL Case select - sql

Question

maybe someone can help me
i have an SQL datebase that is used for logging employees leave. we have some many different shifts, that on our employees table we have 7 fields that represent the days they work. these are a bit data type, 1 for working that day, and 0 for not working.
a second table has all the employees leave. containing employee id, leave date and reason.
i can easily query the employees table and get how many people are to work on any given day of the week, and i can easily query the leave table to see how many people are off on a given date.
what i looking to do is based on the day of the week in the leave table, count how many people are supposed to be in on that day.
the code im trying to make work is
select TBL_Leave.Leave_Date AS 'Date',
datepart(weekday,TBL_Leave.Leave_Date) - 1 AS 'Day Of Week',
count(TBL_Leave.Leave_Date) AS 'Total Off',
case
when datepart(weekday,TBL_Leave.Leave_Date) - 1 = 5 then select SUM(convert(int,Mon)) from TBL_Employees)
else 'Flase'
end
from TBL_Leave
where Leave_Date between '2010-01-01' AND '2010-12-31'
group by TBL_Leave.Leave_Date
but sure enough, it dont work.
im trying to count the number of people working from one table based the the day of the week from a field in another.
any help anyone can give will be great
cheers
Paul
i have this query to get how many people are off on any date
select TBL_Leave.Leave_Date AS 'Date',
datepart(weekday,TBL_Leave.Leave_Date) - 1 AS 'Day Of Week',
count(TBL_Leave.Leave_Date) AS 'Total Off'
from TBL_Leave
where Leave_Date between '2010-01-01' AND '2010-12-31'
group by TBL_Leave.Leave_Date
and this to see how many people are in on any day
select SUM(convert(int,Mon)) as 'Monday',
SUM(convert(int,Tue)) AS 'Tuesday',
SUM(convert(int,Wed)) AS 'Wednesday',
SUM(convert(int,Thu)) AS 'Thursday',
SUM(convert(int,Fri)) AS 'Friday',
SUM(convert(int,Sat)) AS 'Saturday',
SUM(convert(int,Sun)) AS 'Sunday'
from TBL_Employees
where planned = 1

Answer 1

IMHO you should set a view in place as a helper for queries like these:
create view V_EmployeeWorkingDays as
select EmployeeID,
case ShortDayName
when 'Mon' then 1 when 'Tue' then 2 when 'Wed' then 3
when 'Thu' then 4 when 'Fri' then 5 when 'Sat' then 6
when 'Sun' then 7 end as weekday,
IsWorking
from TBL_Employees
unpivot (IstWorking for ShortDayName in (Mon,Tue,Wed,Thu,Fri,Sat,Sun)) p;
Secondly you need the calendar dates within your range. You could use a function like this:
create function F_DateValues(#FromDate datetime, #ToDate datetime)
returns table as
return (
select dateadd(day,Nr-1,#FromDate) as Date
from (select row_number() over (rand()) as Nr
from (values (1),(1),(1),(1)) a
cross join (values (1),(1),(1),(1)) b
cross join (values (1),(1),(1),(1)) c
cross join (values (1),(1),(1),(1)) c) n
where Nr > datediff(day,#FromDate,#ToDate)
);
Now you can put this alltogether:
select d.Date,
isnull(w.CountWorkingPlanned,0)-isnull(l.CountLeaves,0) as CountWorking
from F_DateValue('20101118','20101128') d
left join (select LeaveDate, count(*) as CountLeaves
from TBL_LeaveDate group by LeaveDate) l
on l.LeaveDate = d.Date
left join (select weekday, count(*) as CountWorkingPlanned
from V_EmployeeWorkingDays where IsWorking=1 group by weekday) w
on w.weekday = datepart(weekday,d.Date);
This should be working (not tested - so please don't kill me for typos ;) ).

Answer 2

You should redesign the table layout. As you have a field for each weekday, that means that you have data in the field names. Data belongs inside the table, so you should put that data as rows in a separate table.
Then it's easy to get the data. Example:
select count(*)
from Employees e
left join Leave l on l.EmployeeId = e.EmployeeId and LeaveDate = #Today
left join Workdays w on w.EmployeeId = e.EmployeeId and w.WeekDay = datepart(weekday, #Today)
where l..EmployeeId is null and w.EmployeeId is null

Answer 3

SELECT count(id) FROM employee WHERE monday = true
Seems easy enough unless I still don't get what you need...

Answer 4

Here's a query that might work for you.
The query uses derived queries to get the leave and work counts. I included an UNPIVOT operation on the TBL_Employee data to make it easier to get the employee data. You can avoid this with design changes that have been suggested.
SELECT Leave.Leave_Date, WorkCount, LeaveCount,
WorkCount-LeaveCount AS CountDifference
FROM
(
-- Get Leave counts by date
SELECT Leave_Date, UPPER(LEFT(DATENAME(dw, Leave_Date), 3)) AS WorkDay,
COUNT(*) as LeaveCount
FROM TBL_Leave
WHERE Leave_Date between '2010-01-01' AND '2010-12-31'
GROUP BY Leave_Date, UPPER(LEFT(DATENAME(dw, Leave_Date), 3))
) AS Leave
LEFT OUTER JOIN
(
-- Get Work counts by day of week
SELECT WorkDay, COUNT(*) WorkCount
FROM
(
SELECT EmpID, Mon, Tue, Wed, Thu, Fri, Sat, Sun
FROM TBL_Employees
) p
UNPIVOT
(IsWorking FOR WorkDay IN
(Mon, Tue, Wed, Thu, Fri, Sat, Sun)
)AS unpvt
WHERE unpvt.IsWorking = 1
GROUP BY WorkDay
) AS Work ON Leave.WorkDay = Work.WorkDay -- Join on day of week

Answer 5

thanks for everyones help on this, i have picked up a few tips. i managed to get this sorted last night and when i look at it, i think i made it sound more complicated than it is. here is what i came up with.
create table TEMP_planned (id int null, mon int null, tue int null, wed int null, thur int null, fri int null, sat int null, sun int null)
insert into TEMP_planned (id, mon, tue, wed, thur, fri, sat, sun)
values(1,
(select SUM(convert(int,Mon)) from TBL_Employees where Planned = 1),
(select SUM(convert(int,Tue)) from TBL_Employees where Planned = 1),
(select SUM(convert(int,Wed)) from TBL_Employees where Planned = 1),
(select SUM(convert(int,Thu)) from TBL_Employees where Planned = 1),
(select SUM(convert(int,Fri)) from TBL_Employees where Planned = 1),
(select SUM(convert(int,Sat)) from TBL_Employees where Planned = 1),
(select SUM(convert(int,Sun)) from TBL_Employees where Planned = 1))
select TBL_Leave.Leave_Date,
'Planned' = case DATEPART(dw,TBL_Leave.Leave_Date) - 1
when 1 then (select mon from TEMP_Planned where ID = 1)
when 2 then (select tue from TEMP_Planned where ID = 1)
when 3 then (select wed from TEMP_Planned where ID = 1)
when 4 then (select thur from TEMP_Planned where ID = 1)
when 5 then (select fri from TEMP_Planned where ID = 1)
when 6 then (select sat from TEMP_Planned where ID = 1)
when 7 then (select sun from TEMP_Planned where ID = 1)
end,
COUNT(tbl_leave.Leave_Date) as 'Total Staff Off'
from TBL_Leave
group by TBL_Leave.Leave_Date
drop table temp_planned