How to find last weekday of current month using SQL

How would I calculate the last weekday of the current month given a date using SQL?

I was able to get the last day of current month, but not sure how to do the last weekday programmatically.

I don’t want to generate a calendar look-up table.

Here’s the last day of month code i’m currently using:

declare @date datetime
set @date='1/4/13'
select DATEADD(d, -1, DATEADD(m, DATEDIFF(m, 0, @date) + 1, 0))

Answer

I know it is not the most intuitive or effective or easy way of doing it. But here is my solution to find the last Weekday of the month…

declare @date datetime, @lastDate datetime, @lastWeekDay datetime
set @date='05/4/2014';--'1/1/2014'
set @lastDate = (SELECT DATEADD(d, -1, DATEADD(m, DATEDIFF(m, 0, @date) + 1, 0)));
/* @dayOfWeek represents -- 0-Monday through 7-Sunday */
declare @dayOfWeek INT = (SELECT DATEDIFF(dd, 0, @lastDate) % 7);
/* If last date is sat/sun substract 1 or 2 days from last date */
set @lastWeekDay = (SELECT CASE WHEN @dayOfWeek = 5 THEN DATEADD(dd, -1, @lastDate)
                               WHEN @dayOfWeek = 6 THEN DATEADD(dd, -2, @lastDate)
                               ELSE @lastDate END)
SELECT @lastWeekDay;