He is one for you, it can count any number of selected week days separately and summarised:

DECLARE @year int

DECLARE @DaysToCount VARCHAR(7) -- any combination of 1234567 as per Monday (1) to Sunday (7)

SET @year = 2015

SET @DaysToCount = '357' -- to count Wednesdays, Fridays and Sundays

;WITH ym

AS

(

SELECT CAST(CAST(@year * 100 + m.m AS CHAR(6)) + '01' AS datetime) mfd

FROM (VALUES (1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12)) m(m)

)

, dc

AS

(

SELECT CAST(d-1 AS DATETIME) AS wd

FROM (VALUES (1),(2),(3),(4),(5),(6),(7)) d(d)

WHERE CHARINDEX(CAST(d AS VARCHAR(1)), @DaysToCount,1) > 0

)

-- if you want just a SUM of selected week days per month USE THIS QUERY:

SELECT

MONTH(mfd) AS MonthNo

,DATENAME(MONTH,mfd) AS MonthName

,SUM(DATEDIFF(DAY, wd, DATEADD(DAY, -1, DATEADD(MONTH, 1, mfd))) / 7 -

DATEDIFF(DAY, wd, DATEADD(DAY, -1, mfd)) / 7 ) AS NoOfSelectedWeekDays

FROM ym

CROSS JOIN dc

GROUP BY mfd

ORDER BY mfd

-- if you want list of WeekDays per Month for each week day separately uncomment and

-- USE THIS QUERY instead of above one:

/*

SELECT

MONTH(mfd) AS MonthNo

,DATENAME(MONTH,mfd) AS MonthName

,DATENAME(WEEKDAY,wd) AS WeekDay

,DATEDIFF(DAY, wd, DATEADD(DAY, -1, DATEADD(MONTH, 1, mfd))) / 7 -

DATEDIFF(DAY, wd, DATEADD(DAY, -1, mfd)) / 7 AS NoOfWeekDays

FROM ym

CROSS JOIN dc

ORDER BY mfd , wd

*/