+ INTERVAL

Compatibility
d+ INTERVAL i DAY
Engine	OK	Alternative
mysql	Yes	d+ i
oracle	No	d+ i
postgres	No	d+ i
sqlserver	No	d+ i

d + INTERVAL i DAY returns the date i days after the date d.

You can also add YEAR, MONTH, DAY, HOUR, MINUTE, SECOND

You can also add a negative value.

 DATE '2006-05-20' + INTERVAL 5 DAY   -> DATE '2006-05-25' 
 DATE '2006-05-20' + INTERVAL 5 MONTH -> DATE '2006-10-20' 
 DATE '2006-05-20' + INTERVAL 5 YEAR  -> DATE '2011-05-20'

schema:gisq

In this example we show the date 7 days after the value specified in whn

SELECT whn, (whn) + 7 
  FROM gisq.eclipse

SELECT whn, (whn) + 7 
  FROM eclipse

SELECT whn, whn + DATE(7 day)
  FROM eclipse

SELECT whn, whn + 7 
  FROM eclipse

SELECT whn, whn+INTERVAL 7 DAY
  FROM eclipse