Date/Time Types

Table 1 lists date and time types supported by GaussDB(DWS). For the operators and built-in functions of the types, see Date and Time Processing Functions and Operators.

If the time format of another database is different from that of GaussDB(DWS), modify the value of the DateStyle parameter to keep them consistent.

**Table 1** Date/Time types
Name	Description	Storage Space
DATE	In Oracle compatibility mode, it is equivalent to timestamp(0) and records the date and time. In other modes, it records the date.	In Oracle compatibility mode, it occupies 8 bytes. In Oracle compatibility mode, it occupies 4 bytes.
TIME [(p)] [WITHOUT TIME ZONE]	Specifies the time of day (no date). p indicates the precision after the decimal point. The value ranges from 0 to 6.	8 bytes
TIME [(p)] [WITH TIME ZONE]	Specifies time within one day (with time zone). p indicates the precision after the decimal point. The value ranges from 0 to 6.	12 bytes
TIMESTAMP[(p)] [WITHOUT TIME ZONE]	Specifies the date and time. p indicates the precision after the decimal point. The value ranges from 0 to 6.	8 bytes
TIMESTAMP[(p)][WITH TIME ZONE]	Specifies the date and time (with time zone). TIMESTAMP is also called TIMESTAMPTZ. p indicates the precision after the decimal point. The value ranges from 0 to 6.	8 bytes
SMALLDATETIME	Specifies the date and time (without time zone). The precision level is minute. 31s to 59s are rounded into 1 minute.	8 bytes
INTERVAL DAY (l) TO SECOND (p)	Specifies the time interval (X days X hours X minutes X seconds). l: indicates the precision of days. The value ranges from 0 to 6. To adapt to Oracle syntax, the precision functions are not supported. p: indicates the precision of seconds. The value ranges from 0 to 6. The digit 0 at the end of a decimal number is not displayed.	16 bytes
INTERVAL [FIELDS] [ (p) ]	Specifies the time interval. fields: YEAR, MONTH, DAY, HOUR, MINUTE, SECOND, DAY TO HOUR, DAY TO MINUTE, DAY TO SECOND, HOUR TO MINUTE, HOUR TO SECOND, and MINUTE TO SECOND. p: indicates the precision of seconds. The value ranges from 0 to 6. p takes effect only when fields are SECOND, DAY TO SECOND, HOUR TO SECOND, or MINUTE TO SECOND. The digit 0 at the end of a decimal number is not displayed.	12 bytes
reltime	Relative time interval. The format is: X years X months X days XX:XX:XX The Julian calendar is used. It specifies that a year has 365.25 days and a month has 30 days. The relative time interval needs to be calculated based on the input value. The output format is POSTGRES.	4 bytes

For example:

--Create a table:
CREATE TABLE date_type_tab(coll date);

--Insert data:
INSERT INTO date_type_tab VALUES (date '12-10-2010');

-- View data:
SELECT * FROM date_type_tab;
        coll         
---------------------
 2010-12-10 00:00:00
(1 row)

-- Delete the tables:
DROP TABLE date_type_tab;

--Create a table:
CREATE TABLE time_type_tab (da time without time zone ,dai time with time zone,dfgh timestamp without time zone,dfga timestamp with time zone, vbg smalldatetime);

--Insert data:
INSERT INTO time_type_tab VALUES ('21:21:21','21:21:21 pst','2010-12-12','2013-12-11 pst','2003-04-12 04:05:06');

-- View data:
SELECT * FROM time_type_tab;
    da    |     dai     |        dfgh         |          dfga          |         vbg         
----------+-------------+---------------------+------------------------+---------------------
 21:21:21 | 21:21:21-08 | 2010-12-12 00:00:00 | 2013-12-11 16:00:00+08 | 2003-04-12 04:05:00
(1 row)

-- Delete the tables:
DROP TABLE time_type_tab;

--Create a table:
CREATE TABLE day_type_tab (a int,b INTERVAL DAY(3) TO SECOND (4)); 

--Insert data:
INSERT INTO day_type_tab VALUES (1, INTERVAL '3' DAY);

-- View data:
SELECT * FROM day_type_tab;
 a |   b    
---+--------
 1 | 3 days
(1 row)

-- Delete the tables:
DROP TABLE day_type_tab;

--Create a table:
CREATE TABLE year_type_tab(a int, b interval year (6));

--Insert data:
INSERT INTO year_type_tab VALUES(1,interval '2' year);

-- View data:
SELECT * FROM year_type_tab;
 a |    b    
---+---------
 1 | 2 years
(1 row)

-- Delete the tables:
DROP TABLE year_type_tab;

Date Input

Date and time input is accepted in almost any reasonable formats, including ISO 8601, SQL-compatible, and traditional POSTGRES. The system allows you to customize the sequence of day, month, and year in the date input. Set the DateStyle parameter to MDY to select month-day-year interpretation, DMY to select day-month-year interpretation, or YMD to select year-month-day interpretation.

Remember that any date or time literal input needs to be enclosed with single quotes, and the syntax is as follows:

type [ ( p ) ] 'value'

The p that can be selected in the precision statement is an integer, indicating the number of fractional digits in the seconds column. Table 2 shows some possible inputs for the date type.

**Table 2** Date input
Example	Description
1999-01-08	ISO 8601 (recommended format). January 8, 1999 in any mode
January 8, 1999	Unambiguous in any date input mode
1/8/1999	January 8 in MDY mode. August 1 in DMY mode
1/18/1999	January 18 in MDY mode, rejected in other modes
01/02/03	January 2, 2003 in MDY mode February 1, 2003 in DMY mode February 3, 2001 in YMD mode
1999-Jan-08	January 8 in any mode
Jan-08-1999	January 8 in any mode
08-Jan-1999	January 8 in any mode
99-Jan-08	January 8 in YMD mode, else error
08-Jan-99	January 8, except error in YMD mode
Jan-08-99	January 8, except error in YMD mode
19990108	ISO 8601. January 8, 1999 in any mode
990108	ISO 8601. January 8, 1999 in any mode
1999.008	Year and day of year
J2451187	Julian date
January 8, 99 BC	Year 99 BC

For example:

--Create a table:
CREATE TABLE date_type_tab(coll date);

--Insert data:
INSERT INTO date_type_tab VALUES (date '12-10-2010');

-- View data:
SELECT * FROM date_type_tab;
        coll         
---------------------
 2010-12-10 00:00:00
(1 row)

-- View the date format:
SHOW datestyle;
 DateStyle 
-----------
 ISO, MDY
(1 row)

-- Configure the date format:
SET datestyle='YMD';
SET

-- Insert data:
INSERT INTO date_type_tab VALUES(date '2010-12-11');

-- View data:
SELECT * FROM date_type_tab;
        coll         
---------------------
 2010-12-10 00:00:00
 2010-12-11 00:00:00
(2 rows)

-- Delete the tables:
DROP TABLE date_type_tab;

Times

The time-of-day types are TIME [(p)] [WITHOUT TIME ZONE] and TIME [(p)] [WITH TIME ZONE]. TIME alone is equivalent to TIME WITHOUT TIME ZONE.

If a time zone is specified in the input for TIME WITHOUT TIME ZONE, it is silently ignored.

For details about the time input types, see Table 3. For details about time zone input types, see Table 4.

**Table 3** Time input
Example	Description
05:06.8	ISO 8601
4:05:06	ISO 8601
4:05	ISO 8601
40506	ISO 8601
4:05 AM	Same as 04:05. AM does not affect value
4:05 PM	Same as 16:05. Input hour must be <= 12
04:05:06.789-8	ISO 8601
04:05:06-08:00	ISO 8601
04:05-08:00	ISO 8601
040506-08	ISO 8601
04:05:06 PST	Time zone specified by abbreviation
2003-04-12 04:05:06 America/New_York	Time zone specified by full name

**Table 4** Time zone input
Example	Description
PST	Abbreviation (for Pacific Standard Time)
America/New_York	Full time zone name
-8:00	ISO-8601 offset for PST
-800	ISO-8601 offset for PST
-8	ISO-8601 offset for PST

For example:

SELECT time '04:05:06';
   time   
----------
 04:05:06
(1 row)

SELECT time '04:05:06 PST';
   time   
----------
 04:05:06
(1 row)

SELECT time with time zone '04:05:06 PST';
   timetz    
-------------
 04:05:06-08
(1 row)

Special Values

The special values supported by GaussDB(DWS) are converted to common date/time values when being read. For details, see Table 5.

**Table 5** Special Values
Input String	Applicable Type	Description
epoch	date, timestamp	1970-01-01 00:00:00+00 (Unix system time zero)
infinity	timestamp	Later than any other timestamps
-infinity	timestamp	Earlier than any other timestamps
now	date, time, timestamp	Start time of the current transaction
today	date, timestamp	Today midnight
tomorrow	date, timestamp	Tomorrow midnight
yesterday	date, timestamp	Yesterday midnight
allballs	time	00:00:00.00 UTC

Interval Input

The input of reltime can be any valid interval in TEXT format. It can be a number (negative numbers and decimals are also allowed) or a specific time, which must be in SQL standard format, ISO-8601 format, or POSTGRES format. In addition, the text input needs to be enclosed with single quotation marks ('').

For details, see Table 6.

**Table 6** Interval input
Input	Output	Description
60	2 mons	Numbers are used to indicate intervals. The default unit is day. Decimals and negative numbers are also allowed. Particularly, a negative interval syntactically means how long before.
31.25	1 mons 1 days 06:00:00
-365	-12 mons -5 days
1 years 1 mons 8 days 12:00:00	1 years 1 mons 8 days 12:00:00	Intervals are in POSTGRES format. They can contain both positive and negative numbers and are case-insensitive. Output is a simplified POSTGRES interval converted from the input.
-13 months -10 hours	-1 years -25 days -04:00:00
-2 YEARS +5 MONTHS 10 DAYS	-1 years -6 mons -25 days -06:00:00
P-1.1Y10M	-3 mons -5 days -06:00:00	Intervals are in ISO-8601 format. They can contain both positive and negative numbers and are case-insensitive. Output is a simplified POSTGRES interval converted from the input.
-12H	-12:00:00

For example:

-- Create a table.
CREATE TABLE reltime_type_tab(col1 character(30), col2 reltime);

-- Insert data.
INSERT INTO reltime_type_tab VALUES ('90', '90');
INSERT INTO reltime_type_tab VALUES ('-366', '-366');
INSERT INTO reltime_type_tab VALUES ('1975.25', '1975.25');
INSERT INTO reltime_type_tab VALUES ('-2 YEARS +5 MONTHS 10 DAYS', '-2 YEARS +5 MONTHS 10 DAYS');
INSERT INTO reltime_type_tab VALUES ('30 DAYS 12:00:00', '30 DAYS 12:00:00');
INSERT INTO reltime_type_tab VALUES ('P-1.1Y10M', 'P-1.1Y10M');

-- View data.
SELECT * FROM reltime_type_tab;
              col1              |                col2                 
--------------------------------+-------------------------------------
 1975.25                        | 5 years 4 mons 29 days
 -2 YEARS +5 MONTHS 10 DAYS     | -1 years -6 mons -25 days -06:00:00
 P-1.1Y10M                      | -3 mons -5 days -06:00:00
 -366                           | -1 years -18:00:00
 90                             | 3 mons
 30 DAYS 12:00:00               | 1 mon 12:00:00
(6 rows)

-- Delete tables.
DROP TABLE reltime_type_tab;