SQL Setting Variable for Current Year Month by Combining two VarChar fields using case statement

问题

I am trying to declare a variable for the current year and month based on a field called YEARMO.

It's a 6 character varchar field with the first 4 characters representing the year and the next 2 characters representing the month (ex. February 2018 as 201802).

I need the month variable to have a 0 in front of it if is a month that only has one digit (any month before October). Current code returns '20182' and would like it to return '201802'.

declare @current_month varchar(6)

set @current_month = CAST( year(getdate()) as varchar(4)) 
+ case when  len(CAST( month(getdate()) as varchar(2))) < 1 then '0' + 
CAST( month(getdate()) as varchar(2)) 
else CAST( month(getdate()) as varchar(2))
end

select @current_month;

回答1:

Your code is over complicated. Use right instead:

declare @current_month char(6)
set @current_month = CAST( year(getdate()) as varchar(4)) + right('00' + cast(month(getdate()) as varchar(2)), 2)
select @current_month;

Result:

201802

If you really want to use case instead, you should change the 1 to 2:

set @current_month = CAST( year(getdate()) as varchar(4)) + 
                     case when len(CAST(month(getdate()) as varchar(2))) < 2 then 
                     '0' + CAST( month(getdate()) as varchar(2)) else 
                     CAST( month(getdate()) as varchar(2)) end

回答2:

You can use Convert function if you are looking for current month

select convert(char(6), getdate(), 112)

回答3:

declare @current_month varchar(6)

set @current_month = CAST(year(getdate())*100 + month(getdate()) as varchar(6))

来源：https://stackoverflow.com/questions/48770533/sql-setting-variable-for-current-year-month-by-combining-two-varchar-fields-usin