   TIMESTAMPADD(interval,int_expr,datetime_expr)

Adds the integer expression int_expr to the date or datetime expression
datetime_expr. The unit for int_expr is given by the
interval argument, which should be one of the following values:
FRAC_SECOND,
SECOND,
MINUTE,
HOUR,
DAY,
WEEK,
MONTH,
QUARTER,
or
YEAR.

The interval value may be specified using one of keywords as shown,
or with a prefix of SQL_TSI_. For example, DAY or
SQL_TSI_DAY both are legal.
