DB Software v7.8

Time and Date

Data Type	Size Size (Not Null)	Resolution	Min Value	Max Value	Zero Value	Precision
DATE	8 bytes 4 bytes	day	1000-01-01	9999-12-31	0000-00-00	yyyy-mm-dd
TIME	8 bytes 4 bytes	second	-838:59:59	838:59:59	00:00:00	hhh:mm:ss
TIME(6)	8 bytes 4 bytes	microsecond	-838:59:59.000000	839:59:59.999999	00:00:00.000000	hhh:mm:ss.mmmmmm
DATETIME	12 bytes 8 bytes	second	1000-01-01 00:00:00	9999-12-31 23:59:59	0000-00-00 00:00:00	yyyy-mm-dd hh:mm:ss
DATETIME(6)	12 bytes 8 bytes	microsecond	1000-01-01 00:00:00.000000	9999-12-31 23:59:59.999999	0000-00-00 00:00:00.000000	yyyy-mm-dd hh:mm:ss.mmmmmm
TIMESTAMP	4 bytes 4 bytes	second	1970-01-01 00:00:01	2038-01-19 03:14:07	0000-00-00 00:00:00	hh:mm:ss
TIMESTAMP(6)	8 bytes 8 bytes	microsecond	1970-01-01 00:00:01.000000	2038-01-19 03:14:07.999999	0000-00-00 00:00:00.000000	hh:mm:ss.mmmmmm
YEAR	2 bytes 1 byte	year	1901	2155	0000	yyyy

Any data being ingested that does not match the precision of the destination datatype will be converted. For example, a value like 2020-12-31 23:59:59 being inserted into a column with the datatype of DATE would be converted to 2020-12-31.

Note: It is recommended to use DATETIME or DATETIME(6) column types instead of TIMESTAMP or TIMESTAMP(6) because TIMESTAMP types only support dates through 2038-01-19 as opposed to 9999-12-31 for DATETIME types. This can avoid the need to do potentially time-consuming application and database maintenance and conversion in the future.

Storing Times and Dates

You can use a string literal to store a time value or a date value. When you do this, the literal is implicitly converted to the time or date. For example, if the table t contains a column dt of type DATETIME, you can use the following statement to store the literal.

INSERT INTO t(dt) VALUES ('2020-11-21');

Alternatively, you can use the TO_ Date and Time Functions, such as TO_DATE and TO_TIMESTAMPto explicitly convert a string literal to a time value or a date value.

Inserting or Updating a Column With the Current Timestamp

To allow inserts or updates of a TIMESTAMP, TIMESTAMP(6), DATETIME , or a DATETIME(6) column with the current timestamp, define the column with the clause:

DEFAULT <timefunction>, to insert a column with the current timestamp.
ON UPDATE <timefunction>, to update a column with the current timestamp.
DEFAULT <timefunction> ON UPDATE <timefunction>, to insert and update a column with the current timestamp.

where <timefunction> is one of the following values: NOW(), NOW(6), CURRENT_TIMESTAMP(), CURRENT_TIMESTAMP(6).

Examples

The following example demonstrates the use of DEFAULT CURRENT_TIMESTAMP() in column definition:

CREATE TABLE s(id INT, ts TIMESTAMP DEFAULT CURRENT_TIMESTAMP());
INSERT INTO s(id) VALUES(1);

INSERT INTO s(id) VALUES(2);

SELECT * FROM s;
****
+------+---------------------+
| id   | ts                  |
+------+---------------------+
|    1 | 2020-05-21 09:12:25 |
|    2 | 2020-05-21 09:12:25 |
+------+---------------------+

The following example demonstrates the use of ON UPDATE CURRENT_TIMESTAMP(6) in column definition:

CREATE TABLE s1(id INT, ts DATETIME(6) ON UPDATE CURRENT_TIMESTAMP(6));

INSERT INTO s1(id,ts) VALUES(1,"2017-07-01");

SELECT * FROM s1;
****
+------+----------------------------+
| id   | ts                         |
+------+----------------------------+
|    1 | 2017-07-01 00:00:00.000000 |
+------+----------------------------+

UPDATE s1 SET id = 2 WHERE id = 1;

SELECT * FROM s1;
****
+------+----------------------------+
| id   | ts                         |
+------+----------------------------+
|    2 | 2020-05-21 09:36:47.124979 |
+------+----------------------------+

The following example demonstrates the use of DEFAULT NOW(6) ON UPDATE NOW(6) in column definition:

CREATE TABLE s2(id INT, ts DATETIME(6) DEFAULT NOW(6) ON UPDATE NOW(6));

INSERT INTO s2(id) VALUES(1);

INSERT INTO s2(id) VALUES(2);

SELECT * FROM s2;
****
+------+----------------------------+
| id   | ts                         |
+------+----------------------------+
|    2 | 2020-05-21 11:21:30.998275 |
|    1 | 2020-05-21 11:21:30.992868 |
+------+----------------------------+

UPDATE s2 SET id = 2 WHERE id = 1;

SELECT * FROM s2;
****
+------+----------------------------+
| id   | ts                         |
+------+----------------------------+
|    2 | 2020-05-21 11:21:30.998275 |
|    2 | 2020-05-21 11:23:39.134793 |
+------+----------------------------+

Warning

Prior to SingleStore 7, when you inserted or updated a record, the first TIMESTAMP or TIMESTAMP(6) column would automatically be populated with the current timestamp. Such columns did not use DEFAULT CURRENT_TIMESTAMP() or ON UPDATE CURRENT_TIMESTAMP() clause in their column definitions. In SingleStore 7 and later, this behavior has been deprecated; TIMESTAMP or TIMESTAMP(6) columns without these clauses will be populated with a NULL value instead of the current timestamp. For instance, NULL values are populated in the ts column in the following example, when run on SingleStore 7 or later.

CREATE TABLE r(d DATETIME(6), ts TIMESTAMP(6), id INT);

INSERT r(d, id) VALUES("2017-07-01", 1);

SELECT * FROM r;
****
+----------------------------+----------------------------+------+
| d                          | ts                         | id   |
+----------------------------+----------------------------+------+
| 2017-07-01 00:00:00.000000 | NULL                       |    1 |
+----------------------------+----------------------------+------+

UPDATE r SET id = 2 WHERE id = 1;

SELECT * FROM r;
****
+----------------------------+----------------------------+------+
| d                          | ts                         | id   |
+----------------------------+----------------------------+------+
| 2017-07-01 00:00:00.000000 | NULL                       |    2 |
+----------------------------+----------------------------+------+

The explicit_defaults_for_timestamp Variable

The variable explicit_defaults_for_timestamp determines if certain nonstandard behaviors for default values and NULL-value are disabled for the TIMESTAMP column. By default, the variable is enabled, which disables the nonstandard behaviors.

If the explicit_defaults_for_timestamp variable is enabled, SingleStore DB handles the TIMESTAMP column behavior as follows:

Assigning a TIMESTAMP column value of NULL does not set it to the current timestamp. To set to the current timestamp, set the TIMESTAMP column to CURRENT_TIMESTAMP() or NOW().
If the TIMESTAMP column is not declared as NOT NULL, then it is automatically declared with the NULL attribute and permits NULL values. Assigning a value of NULL to the column sets it to NULL, not the current timestamp.
TIMESTAMP column declared with the NOT NULL attribute do not permit NULL values.
TIMESTAMP columns explicitly declared with the NOT NULL attribute and without an explicit DEFAULT attribute are treated as having no default value.
To declare TIMESTAMP column with the DEFAULT CURRENT_TIMESTAMP() or ON UPDATE CURRENT_TIMESTAMP() attributes, these must be explicitly specified.
The first TIMESTAMP column in a table is handled in the same way as the TIMESTAMP columns following the first one.

If the explicit_defaults_for_timestamp variable is disabled, SingleStore DB handles the TIMESTAMP column behavior as follows:

If the TIMESTAMP column is not declared as NULL, then it is automatically declared with the NOT NULL attribute. Assigning a value of NULL to the column is permitted and sets the column to the current timestamp.
The first TIMESTAMP column in a table, if not declared as NULL, DEFAULT CURRENT_TIMESTAMP() or ON UPDATE CURRENT_TIMESTAMP(), is automatically declared with the DEFAULT CURRENT_TIMESTAMP() and ON UPDATE CURRENT_TIMESTAMP() attributes.
TIMESTAMP columns following the first one, if not declared with the NULL attribute or a DEFAULT attribute, are automatically declared as DEFAULT“0000-00-00 00:00:00” (the “zero” timestamp).

In this section: