ROUND_TIMESTAMP

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

The schema is SYSIBM.

expression

FL 507 An expression that returns a value of any of the following built-in data types: a date, 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 with an actual length that is not greater than 255 bytes. A time zone in a string representation of a timestamp is ignored. For the valid formats of string representations of dates and timestamps, see String representations of datetime values.

Passthrough-only support: FL 507 If expression is a date, Db2 passes the function through to IBM® Db2 Analytics Accelerator as a passthrough-only expression. For more information, see Accelerating queries with passthrough-only expressions.

format-string

An expression that returns a built-in character string or graphic string data type, with a length that is not greater than 255 bytes. 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. format-string must be a valid template for a timestamp, and not include leading or trailing blanks.

Allowable values for format-string are listed in the following table.

Table 1. ROUND_TIMESTAMP and TRUNC_TIMESTAMP format models
Format model	Description of rounding or truncating for the format model	ROUND_TIMESTAMP example	TRUNC_TIMESTAMP example
CC SCC	Century. One greater than the first two digits of a four digit year. For ROUND_TIMESTAMP, 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. For ROUND_TIMESTAMP, 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. For ROUND_TIMESTAMP, 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. For ROUND_TIMESTAMP, 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. For ROUND_TIMESTAMP, 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. For ROUND_TIMESTAMP, 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. For ROUND_TIMESTAMP, 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. For ROUND_TIMESTAMP, 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: 2000-06-21-12.12.30.000000 Result: 2000-06-15-00.00.00.000000
DDD DD J	Day. For ROUND_TIMESTAMP, 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. For ROUND_TIMESTAMP, 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. For ROUND_TIMESTAMP, 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. For ROUND_TIMESTAMP, 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. For ROUND_TIMESTAMP, 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

If expression does not have data type TIMESTAMP WITHOUT TIME ZONE, expression is cast as follows:

If expression is a TIMESTAMP WITH TIME ZONE value, expression is cast to TIMESTAMP WITHOUT TIME ZONE, with the same precision as expression.
Otherwise, expression is cast to TIMESTAMP(6) WITHOUT TIME ZONE.

The result of the function has the same data type as the data type to which expression is cast.

The result can be null; if any argument is null, the result is the null value.

The result CCSID is the appropriate CCSID of the argument encoding scheme and the result subtype is the appropriate subtype of the CCSID.

Examples

Set the host variable RND_TMSTMP with the input timestamp rounded to the nearest year value.

   SET :RND_TMSTMP = ROUND_TIMESTAMP(TIMESTAMP_FORMAT('2000-08-14 17:30:00', 
                                              'YYYY-MM-DD HH24:MI:SS'), 'YEAR');

The value set is '2001-01-01-00.00.00.000000'.

Assume PRSTSZ is an SQL variable with the TIMESTAMP WITH TIME ZONE value '2008-04-15.20.00.000000-08:30'. The input value is first cast to TIMESTAMP WITHOUT TIME ZONE (as '2008-04-15.20.00.000000') for the ROUND_TIMESTAMP function.
```
SELECT ROUND_TIMESTAMP(PRSTSZ) 
	FROM PROJECT;
```
The ROUND_TIMESTAMP function returns a TIMESTAMP WITHOUT TIME ZONE value of '2008-04-16.00.00.000000'.