Our patching schedules are algorithmic – the 1^st Tuesday of the month, the 3^rd Wednesday of the month, etc. But that’s not particularly useful for notifying end users or for us to verify functionality after patching.

Long term, I think we can pull the source data from a database and create appointment items each month for whatever list of servers will be patched that month based on a relative date (so no one has to add new servers or remove decommissioned servers). But, short term? I really wanted a way to see what date a server would be patched. So I created a but of a convoluted spreadsheet to produce this information based on a list of servers and patching schedule patterns.

There are two “extra” tabs used – “Dates” used to say what month and year I want the patching dates for

And “ServerData” which provides a cross-reference between the server names and a useful description.

There are then a series of formulae used to add columns to our source data. First, the “Function” is populated in column G with a VLOOKUP =VLOOKUP(B2,ServerData!A:B,2,FALSE)

Columns I and J break the “1^st Saturday” into the two components – week of month and day of week –

I =LEFT(C2,3)
J =RIGHT(C2,LEN(C2)-4)

Columns K and L then map these components into numeric values I can use in a formula:

K =IF(I2=”1st”,1,IF(I2=”2nd”,2,IF(I2=”3rd”,3,IF(I2=”4th”,4,”Unscheduled”))))
L =IF(J2=”Sunday”,1,IF(J2=”Monday”,2,IF(J2=”Tuesday”,3,IF(J2=”Wednesday”,4,IF(J2=”Thursday”,5,IF(J2=”Friday”,6,IF(J2=”Saturday”,7,”Unscheduled”)))))))

And finally a formula in column H that turns the week of month and day of week values into an actual date within the month and year on the “Dates” tab:

H =DATE(Dates!$B$2,Dates!$A$2,1+7*K2)-WEEKDAY(DATE(Dates!$B$2,Dates!$A$2,8-L2))

Voila – I have a spreadsheet that says we should expect to see this specific list of servers being patched tonight.