ROUND_TIMESTAMP

The ROUND_TIMESTAMP function returns a timestamp that is the expression rounded to the unit specified by the format-string. If format-string is not specified, expression is rounded to the nearest day, as if 'DD' was specified for format-string.


                                   .-,--'DD'----------.      
>>-ROUND_TIMESTAMP--(--expression--+------------------+--)-----><
                                   '-,--format-string-'

expression: An expression that returns a value of one of the following built-in data types: a timestamp, a character-string, or a graphic-string.; If expression is a character or graphic string, it must not be a CLOB or DBCLOB and its value must be a valid string representation of a timestamp. For the valid formats of string representations of timestamps, see String representations of datetime values.
format-string: An expression that returns a built-in character string data type or graphic string data type that is not a CLOB or DBCLOB. format-string contains a template of how the timestamp represented by expression should be rounded. For example, if format-string is 'DD', the timestamp that is represented by expression is rounded to the nearest day. Leading and trailing blanks are removed from the string, and the resulting substring must be a valid template for a timestamp. The resulting value is then folded to uppercase, so the characters in the value may be in any case. The resulting substring must be a valid format element for a timestamp.
Allowable values for format-string are listed in Table 1.

The result of the function is a TIMESTAMP. If either argument can be null, the result can be null; if either argument is null, the result is the null value.

Table 1. ROUND_TIMESTAMP and TRUNC_TIMESTAMP format models
Format model	Rounding or truncating unit	ROUND_TIMESTAMP example	TRUNC_TIMESTAMP example
CC SCC	One greater than the first two digits of a four digit year. (Rounds up on the 50th year of the century)	Input value: 1897-12-04-12.22.22.000000 Result: 1901-01-01-00.00.00.000000	Input value: 1897-12-04-12.22.22.000000 Result: 1801-01-01-00.00.00.000000
SYYYY YYYY YEAR SYEAR YYY YY Y	Year (Rounds up on July 1 to January 1st of the next year)	Input value: 1897-12-04-12.22.22.000000 Result: 1898-01-01-00.00.00.000000	Input value: 1897-12-04-12.22.22.000000 Result: 1897-01-01-00.00.00.000000
IYYY IYY IY I	ISO year (Rounds up on July 1 to the first day of the next ISO year. The first day of the ISO year is defined as the Monday of the first ISO week.)	Input value: 1897-12-04-12.22.22.000000 Result: 1898-01-03-00.00.00.000000	Input value: 1897-12-04-12.22.22.000000 Result: 1897-01-04-00.00.00.000000
Q	Quarter (Rounds up on the 16th day of the second month of the quarter)	Input value: 1999-06-04-12.12.30.000000 Result: 1999-07-01-00.00.00.000000	Input value: 1999-06-04-12.12.30.000000 Result: 1999-04-01-00.00.00.000000
MONTH MON MM RM	Month (Rounds up on the 16th day of the month)	Input value: 1999-06-18-12.12.30.000000 Result: 1999-07-01-00.00.00.000000	Input value: 1999-06-18-12.12.30.000000 Result: 1999-06-01-00.00.00.000000
WW	Same day of the week as the first day of the year (Rounds up on the 12th hour of the 4th day of the week, with respect to the first day of the year)	Input value: 2000-05-05-12.12.30.000000 Result: 2000-05-06-00.00.00.000000	Input value: 2000-05-05-12.12.30.000000 Result: 2000-04-29-00.00.00.000000
IW	Same day of the week as the first day of the ISO year (Rounds up on the 12th hour of the 4th day of the week, with respect to the first day of the ISO year)	Input value: 2000-05-05-12.12.30.000000 Result: 2000-05-08-00.00.00.000000	Input value: 2000-05-05-12.12.30.000000 Result: 2000-05-01-00.00.00.000000
W	Same day of the week as the first day of the month (Rounds up on the 12th hour of the 4th day of the week, with respect to the first day of the month)	Input value: 2000-06-21-12.12.30.000000 Result: 2000-06-22-00.00.00.000000	Input value: 2000-06-22-12.12.30.000000 Result: 2000-06-15-00.00.00.000000
DDD DD J	Day (Rounds up on the 12th hour of the day)	Input value: 2000-05-17-12.59.59.000000 Result: 2000-05-18-00.00.00.000000	Input value: 2000-05-17-12.59.59.000000 Result: 2000-05-17-00.00.00.000000
DAY DY D	Starting day of the week (Rounds up with respect to the 12th hour of the 4th day of the week. The first day of the week is always Sunday)	Input value: 2000-05-17-12.59.59.000000 Result: 2000-05-21-00.00.00.000000	Input value: 2000-05-17-12.59.59.000000 Result: 2000-05-14-00.00.00.000000
HH HH12 HH24	Hour (Rounds up at 30 minutes)	Input value: 2000-05-17-23.59.59.000000 Result: 2000-05-18-00.00.00.000000	Input value: 2000-05-17-23.59.59.000000 Result: 2000-05-17-23.00.00.000000
MI	Minute (Rounds up at 30 seconds)	Input value: 2000-05-17-23.58.45.000000 Result: 2000-05-17-23.59.00.000000	Input value: 2000-05-17-23.58.45.000000 Result: 2000-05-17-23.58.00.000000
SS	Second (Rounds up at 500000 microseconds)	Input value: 2000-05-17-23.58.45.500000 Result: 2000-05-17-23.58.46.000000	Input value: 2000-05-17-23.58.45.500000 Result: 2000-05-17-23.58.45.000000
Note: The ISO year starts on the first day of the first ISO week of the year. This can be up to three days before January 1st or three days after January 1st. See WEEK_ISO for details.

Example

Set the host variable RND_TMSTMP with the current year rounded to the nearest month value.
```
  SET :RND_TMSTMP = ROUND_TIMESTAMP('2000-03-18-17.30.00', 'MONTH');
```
Host variable RND_TMSTMP is set with the value 2000-04-01-00.00.00.000000.