sql server - Get previous month in SQL when given a varchar -

if have varchar looks following:

'201503' 

how similiar varchar representation of previous month? e,g, '201502' ? if month falls on january i.e. '201501' should '201412'

some appreciated :)

try this:

declare @dt varchar(8) = '201501'  select left(convert(varchar(8), dateadd(m, -1, @dt + '01'), 112), 6) 

output:

201412

using dateadd can calculate previous month. function conveniently accepts string argument. convert used convert result yyyymmdd format.