Get monthly attendance for an employee - sql-server

Question

I have a query that a guy helped here in developing which gives fine result. I want to use this query in a function which later I want to use in a procedure.
CREATE FUNCTION [dbo].[fnGetWorkedDays] (#StartDate datetime, #EndDate datetime)
RETURNS int
AS
BEGIN
DECLARE #dateFrom datetime
DECLARE #dateTo datetime
SET #dateFrom = #StartDate
SET #dateTo = #EndDate
DECLARE #DAYSWORKED INT
SELECT #DAYSWORKED = (
SELECT EmpId, COUNT(*) as DaysWorked
FROM
(
SELECT DISTINCT EmpId,CAST(TimeIn AS DATE) AS [Date]
FROM myTable
WHERE TimeIn IS NOT NULL
AND CAST(TimeIn AS DATE) BETWEEN #StartDate AND #EndDate
)T
GROUP BY EmpId
ORDER BY EmpId)
RETURN ISNULL(#DAYSWORKED,0)
END
The very first error I am getting is that
Msg 1033, Level 15, State 1, Procedure fnGetWorkedDays, Line 24
The ORDER BY clause is invalid in views, inline functions, derived tables, subqueries, and common table expressions, unless TOP, OFFSET or FOR XML is also specified.
I removed ORDER BY then I got another error says
Msg 116, Level 16, State 1, Procedure fnGetWorkedDays, Line 25
Only one expression can be specified in the select list when the subquery is not introduced with EXISTS.

Answer 1

I suggest you to go though this to understand more on table valued functions vs scalar valued function Difference between scalar, table-valued, and aggregate functions in SQL server?
Regarding your scenario, you should be writing a table values function for this like following.
CREATE FUNCTION [dbo].[fnGetWorkedDays]
(
#StartDate AS DATETIME,
#EndDate datetime
)
RETURNS TABLE
AS
RETURN
SELECT EmpId, COUNT(*) as DaysWorked
FROM
(
SELECT DISTINCT EmpId,CAST(TimeIn AS DATE) AS [Date]
FROM myTable
WHERE TimeIn IS NOT NULL
AND CAST(TimeIn AS DATE) BETWEEN #StartDate AND #EndDate
)T
GROUP BY EmpId
To use the function you can write your queries like following.
DECLARE #StartDate datetime
DECLARE #EndDate datetime
SET #StartDate = '2018-01-01'
SET #EndDate = '2018-01-31'
select * from [dbo].[fnGetWorkedDays](#StartDate,#EndDate)
If you want this to work as a scalar value function, in that case you need to pass EmpId as parameter like following.
CREATE FUNCTION [dbo].[fnGetWorkedDaysEmpWise]
(
#StartDate AS DATETIME,
#EndDate datetime,
#EmpId INT
)
RETURNS INT
AS
BEGIN
DECLARE #RetunCount INT
SELECT #RetunCount = COUNT(DISTINCT CAST(TimeIn AS DATE))
FROM myTable
WHERE TimeIn IS NOT NULL
AND CAST(TimeIn AS DATE) BETWEEN #StartDate AND #EndDate
AND EmpID=#EmpId
RETURN #RetunCount
END
And you can use it directly in your select clause like following.
DECLARE #StartDate datetime
DECLARE #EndDate datetime
SET #StartDate = '2018-01-01'
SET #EndDate = '2018-01-31'
SELECT [dbo].[fnGetWorkedDaysEmpWise](#StartDate,#EndDate,1)

Answer 2

Is this what you are looking for .?
CREATE FUNCTION [dbo].[fnGetWorkedDays] (#StartDate datetime, #EndDate datetime)
RETURNS #DaysWorked TABLE
(
Empid Int,
DaysWorked Int
)
AS
BEGIN
insert into #DaysWorked (Empid,DaysWorked)
SELECT EmpId, COUNT(*) as DaysWorked
FROM
(
SELECT DISTINCT EmpId,CAST(TimeIn AS DATE) AS [Date]
FROM myTable
WHERE TimeIn IS NOT NULL
AND CAST(TimeIn AS DATE) BETWEEN #StartDate AND #EndDate
)T
GROUP BY EmpId
ORDER BY EmpId
RETURN
END
select * from [fnGetWorkedDays]('2018-01-01','2018-01-31')