MSSQL Edit date (YEAR, MONTH) in one command

Question

I need manipulate with time in one command. I have this date "15.02.2013" and now i need this time change on this "15.01.2012". Date is dynamic stats for me. i need change time with this functions (GATEDATE, YEAR, MONTH) or others.

INPUT:

"15.02.2013"

I need this output:

"15.01.2012"

Can you help me please?

Answer 1

You can do a double DATEADD on the same value.

I.e.

SELECT DATEADD(year, -1, DATEADD(month, -1, @date_from)) FROM Table1

The inner DATEADD is your original, which subtracts the month. This is then wrapped in a second DATEADD which subtracts the year. Alternatively, if it's always 1 year and one month, you could easily subtract 13 months:

SELECT DATEADD(month, -13, @date_from))

You could even choose to have a computed column in your table using the function to calculate the date.