I have a date column like this.
2012-01-28
2012-01-28
2012-01-28
2012-01-28
2012-01-28
2012-01-28
2012-01-28
2012-01-28
2012-01-28
2012-01-28
2012-01-28
2012-01-28
2012-01-29
2012-01-29
2012-01-29
2012-01-29
2012-01-29
2012-01-29
....
2016-12-31
2016-12-31
2016-12-31
2016-12-31
I want to convert it into any of the below format: i.e get the unique yyyy-mm
2012-01 or 2012-Jan or Jan
2012-02 or 2012-Feb or Feb
2012-03
...
2016-12 or 2012-Dec or Dec