Question

I have a column with datatype Date time and so contains value such as:06-FEB-12 02.39.11.000000000 PM. I wanted to only modify the date for all the rows that are dated 06-FEB-12 to 25-JAN-12 preserving the time.

Can I do the same through an update query?

Answer 1

I’m a bit confused about the data type. You state the the column is a DATE but the sample data you provided has fractional seconds which implies a TIMESTAMP.

You can subtract exactly 12 days from all the rows that have a DATE or TIMESTAMP on February 6, 2012 which will yield DATE or TIMESTAMP values on January 25, 2012.

UPDATE table_name
   SET column_name = column_name - interval '12' day
 WHERE trunc( column_name ) = date '2012-02-06';