SQL DATE_ADD() function adds a specified time interval to a date.

Table – orders

+—–+—–+——-+———————+
| oid | uid | items | date                |
+—–+—–+——-+———————+
|   1 |   1 | AAAA  | 2007-05-16 00:00:00 |
+—–+—–+——-+———————+

Example

mysql> SELECT DATE_ADD(date, INTERVAL 4 DAY) FROM orders;
+——————————–+
| DATE_ADD(date, INTERVAL 4 DAY) |
+——————————–+
| 2007-05-20 00:00:00            |
+——————————–+
1 row in set (0.01 sec)

Unit

MICROSECOND
SECOND
MINUTE
HOUR
DAY
WEEK
MONTH
QUARTER
YEAR
SECOND_MICROSECOND
MINUTE_MICROSECOND
MINUTE_SECOND
HOUR_MICROSECOND
HOUR_SECOND
HOUR_MINUTE
DAY_MICROSECOND
DAY_SECOND
DAY_MINUTE
DAY_HOUR