Date and time functions

systimestamp

systimestamp() - offset from UTC Epoch in microseconds.

Arguments

• systimestamp() does not require arguments.

Description

Calculates UTC timestamp using system's real time clock. The value is affected by discontinuous jumps in the system time (e.g., if the system administrator manually changes the system time).

Return value

Return value type is timestamp.

Examples:

Insert current system timestamp

INSERT INTO readings

VALUES(systimestamp(), 123.5);

ts	reading
2020-01-02T19:28:48.727516Z	123.5

Query based on last minute

SELECT * FROM readings

WHERE datetime > systimestamp() - 60000000L;

sysdate

sysdate() - returns the timestamp of the host system as a date with millisecond precision.

Arguments

• sysdate() does not require arguments.

Description

Calculates UTC date with millisecond precision using system's real time clock. The value is affected by discontinuous jumps in the system time (e.g., if the system administrator manually changes the system time).

Return value

Return value type is date.

Examples:

Insert current system date along with a value

INSERT INTO readings

VALUES(sysdate(), 123.5);

sysdate	reading
2020-01-02T19:28:48.727516Z	123.5

Query based on last minute

SELECT * FROM readings

WHERE date_time > sysdate() - 60000000L;

to_timestamp

to_timestamp(string, format) - converts string to timestamp by using the supplied format to extract the value.

Arguments

• string is any string that represents a date and/or time.
• format is a string that describes the timestamp format in which string is expressed.

Description

Will convert a string to timestamp using the format definition passed as a parameter. When the format definition does not match the string input, the result will be null.

For more information about recognized timestamp formats, see the date and timestamp format section.

Return value

Return value type is timestamp

Examples

string matches format

SELECT to_timestamp('2020-03-01:15:43:21', 'yyyy-MM-dd:HH:mm:ss')

FROM long_sequence(1);

to_timestamp
2020-03-01T15:43:21.000000Z

string does not match format

SELECT to_timestamp('2020-03-01:15:43:21', 'yyyy')

FROM long_sequence(1);

to_timestamp
null

Using with INSERT

INSERT INTO measurements

values(to_timestamp('2019-12-12T12:15', 'yyyy-MM-ddTHH:mm'), 123.5);

timestamp	value
2019-12-12T12:15:00.000000Z	123.5

to_date

to_date(string, format) - converts string to date by using the supplied format to extract the value.

Arguments

• string is any string that represents a date and/or time.
• format is a string that describes the date format in which string is expressed.

Description

Will convert a string to date using the format definition passed as a parameter. When the format definition does not match the string input, the result will be null.

For more information about recognized timestamp formats, see the date and timestamp format section.

Return value

Return value type is date

Examples

string matches format

SELECT to_date('2020-03-01:15:43:21', 'yyyy-MM-dd:HH:mm:ss')

FROM long_sequence(1);

to_date
2020-03-01T15:43:21.000Z

string does not match format

SELECT to_date('2020-03-01:15:43:21', 'yyyy')

FROM long_sequence(1);

to_date
null

Using with INSERT

INSERT INTO measurements

values(to_date('2019-12-12T12:15', 'yyyy-MM-ddTHH:mm'), 123.5);

date	value
2019-12-12T12:15:00.000Z	123.5

to_str

to_str(value, format) - converts date or timestamp value to a string in the specified format

Arguments

• value is any date or timestamp
• format is a timestamp format.

Description

Will convert a date or timestamp value to a string using the format definition passed as a parameter. When elements in the format definition are unrecognized, they will be passed-through as string.

For more information about recognized timestamp formats, see the date and timestamp format section.

Return value

Return value type is string

Examples

• Basic example

SELECT to_str(systimestamp(), 'yyyy-MM-dd') FROM long_sequence(1);

to_str
2020-03-04

• With unrecognized timestamp definition

SELECT to_str(systimestamp(), 'yyyy-MM-dd gooD DAY 123') FROM long_sequence(1);

to_str
2020-03-04 gooD DAY 123

dateadd

dateadd(period, n, startDate) - adds time to a date or timestamp

Arguments

• period is a char. Period to be added. Available periods are s, m, h, d, M, y.
• n is an int. Number of periods to add.
• startDate is a timestamp or date. Timestamp to add the periods to.

Description

Adds n period to startDate.

Return value

Return value type is timestamp

Examples

Adding hours

SELECT systimestamp(), dateadd('h', 2, systimestamp())

FROM long_sequence(1);

systimestamp	dateadd
2020-04-17T00:30:51.380499Z	2020-04-17T02:30:51.380499Z

Adding days

SELECT systimestamp(), dateadd('d', 2, systimestamp())

FROM long_sequence(1);

systimestamp	dateadd
2020-04-17T00:30:51.380499Z	2020-04-19T00:30:51.380499Z

Adding months

SELECT systimestamp(), dateadd(`M`, 2, systimestamp())

FROM long_sequence(1);

systimestamp	dateadd
2020-04-17T00:30:51.380499Z	2020-06-17T00:30:51.380499Z

datediff

datediff(period, date1, date2) - returns the difference between two dates or timestamps

Arguments

• period is a char. Period to be added. Available periods are s, m, h, d, M, y.
• date1 and date2 are date or timestamp. Dates to compare

Description

Returns the absolute number of period between date1 and date2.

Return value

Return value type is int

Examples

Difference in days

select datediff(

'd',

to_timestamp('2020-01-23','yyyy-MM-dd'),

to_timestamp('2020-01-27','yyyy-MM-dd'))

from long_sequence(1);

datediff
4

Difference in months

```questdb-sql

select datediff(

'M',

to_timestamp('2020-01-23','yyyy-MM-dd'),

to_timestamp('2020-02-24','yyyy-MM-dd'))

from long_sequence(1);

datediff
1

millis

millis(value) - milliseconds of the second on a 0-999 scale

Parameters

• value is any timestamp or date

Description

millis(value) returns the millis of the second for a given date or timestamp from 0 to 999

Return value

Return value type is int

Examples

Millis of the second

SELECT millis(

to_timestamp('2020-03-01:15:43:21.123456', 'yyyy-MM-dd:HH:mm:ss.SSSUUU'))

FROM long_sequence(1);

millis
123

Using in an aggregation

select millis(ts), count() from transactions;

second	count
0	2323
1	6548
...	...
998	9876
999	2567

micros

micros(value) - microseconds of the millisecond on a 0-999 scale

Parameters

• value is any timestamp or date

Description

micros(value) returns the micros of the millisecond for a given date or timestamp from 0 to 999

Return value

Return value type is int

Examples

Micros of the second

SELECT micros(to_timestamp('2020-03-01:15:43:21.123456', 'yyyy-MM-dd:HH:mm:ss.SSSUUU'))

FROM long_sequence(1);

millis
456

Using in an aggregation

select micros(ts), count() from transactions;

second	count
0	2323
1	6548
...	...
998	9876
999	2567

second

second(value) - second of the minute on a 0-59 scale

Parameters

• value is any timestamp or date

Description

second(value) returns the second of the minute for a given date or timestamp from 0 to 59

Return value

Return value type is int

Examples

Second of the minute

SELECT second(to_timestamp('2020-03-01:15:43:21', 'yyyy-MM-dd:HH:mm:ss'))

FROM long_sequence(1);

second
43

Using in an aggregation

select second(ts), count() from transactions;

second	count
0	2323
1	6548
...	...
58	9876
59	2567

minute

minute(value) - minute of hour on a 0-59 scale

Parameters

• value is any timestamp or date

Description

minute(value) returns the minute of the hour for a given date or timestamp from 0 to 59

Return value

Return value type is int

Examples

Minute of the hour

SELECT minute(to_timestamp('2020-03-01:15:43:21', 'yyyy-MM-dd:HH:mm:ss'))

FROM long_sequence(1);

minute
43

Using in an aggregation

select minute(ts), count() from transactions;

minute	count
0	2323
1	6548
...	...
58	9876
59	2567

hour

hour(value) - hour of day on a 0-23 scale

Parameters

• value is any timestamp or date

Description

hour(value) returns the hour of day for a given date or timestamp from 0 to 23

Return value

Return value type is int

Examples

Hour of the day

SELECT hour(to_timestamp('2020-03-01:15:43:21', 'yyyy-MM-dd:HH:mm:ss'))

FROM long_sequence(1);

hour
12

Using in an aggregation

select hour(ts), count() from transactions;

hour	count
0	2323
1	6548
...	...
22	9876
23	2567

day

day(value) - day of month on a 1 to 31 scale

Parameters

• value is any timestamp or date

Description

day(value) returns the day of month for a given date or timestamp from 0 to 23

Return value

Return value type is int

Examples

Day of the month

SELECT day(to_timestamp('2020-03-01:15:43:21', 'yyyy-MM-dd:HH:mm:ss'))

FROM long_sequence(1);

day
01

Using in an aggregation

select day(ts), count() from transactions;

day	count
1	2323
2	6548
...	...
30	9876
31	2567

month

month(value) - month of year on a 1-12 scale

Parameters

• value is any timestamp or date

Description

month(value) returns the month of year for a given date or timestamp from 1 to 12

Return value

Return value type is int

Examples

Month of the year

SELECT month(to_timestamp('2020-03-01:15:43:21', 'yyyy-MM-dd:HH:mm:ss'))

FROM long_sequence(1);

month
03

Using in an aggregation

select month(ts), count() from transactions;

month	count
1	2323
2	6548
...	...
11	9876
12	2567

year

year(value) - year of a timestamp

Parameters

• value is any timestamp or date

Description

year(value) returns the year for a given date or timestamp

Return value

Return value type is int

Examples

Year

SELECT year(to_timestamp('2020-03-01:15:43:21', 'yyyy-MM-dd:HH:mm:ss'))

FROM long_sequence(1);

year
2020

Using in an aggregation

select month(ts), count() from transactions;

year	count
2015	2323
2016	9876
2017	2567

is_leap_year

is_leap_year(value) - flags a leap year

Parameters

• value is any timestamp or date

Description

is_leap_year(value) returns true if the year of value is a leap year, false otherwise.

Return value

Return value type is boolean

Examples

select year(ts), is_leap_year(ts) from myTable;

year	is_leap_year
2020	true
2021	false
2022	false
2023	false
2024	true
2025	false

days_in_month

days_in_month(value) - counts days in month

Parameters

• value is any timestamp or date

Description

days_in_month(value) returns the count of days in a the month.

Return value

Return value type is int

Examples

select month(ts), days_in_month(ts) from myTable;

month	days_in_month
4	30
5	31
6	30
7	31
8	31

day_of_week

day_of_week(value) - day number in the week starting on Monday

Parameters

• value is any timestamp or date

Description

day_of_week(value) returns the day number in a week from 1 (Monday) to 7 (Sunday)

Return value

Return value type is int

Examples

select to_str(ts,'EE'),day_of_week(ts) from myTable;

day	day_of_week
Monday	1
Tuesday	2
Wednesday	3
Thursday	4
Friday	5
Saturday	6
Sunday	7

day_of_week_sunday_first

day_of_week_sunday_first(value) - day number in the week starting on Sunday

Parameters

• value is any timestamp or date

Description

day_of_week_sunday_first(value) returns the day number in a week from 1 (Sunday) to 7 (Saturday)

Return value

Return value type is int

Examples

select to_str(ts,'EE'),day_of_week_sunday_first(ts) from myTable;

day	day_of_week_sunday_first
Monday	2
Tuesday	3
Wednesday	4
Thursday	5
Friday	6
Saturday	7
Sunday	1

Date and Timestamp format

Format is a combination of letters from table below combined with arbitrary text. Format letters are case-sensitive and are used as is (e.g. without any prefix)

Letter	Date or Time Component	Presentation	Examples
G	Era designator	Text	AD
y	Year	Year	1996; 96
Y	Week year	Year	2009; 09
M	Month in year	Month	July; Jul; 07
w	Week in year	Number	27
W	Week in month	Number	2
D	Day in year	Number	189
d	Day in month	Number	10
F	Day of week in month	Number	2
E	Day name in week	Text	Tuesday; Tue
u	Day number of week (1 = Monday, ..., 7 = Sunday)	Number	1
a	Am/pm marker	Text	PM
H	Hour in day (0-23)	Number	0
k	Hour in day (1-24)	Number	24
K	Hour in am/pm (0-11)	Number	0
h	Hour in am/pm (1-12)	Number	12
m	Minute in hour	Number	30
s	Second in minute	Number	55
S	Millisecond	Number	978
z	Time zone	General time zone	Pacific Standard Time; PST; GMT-08:00
Z	Time zone	RFC 822 time zone	-0800
X	Time zone	ISO 8601 time zone	-08; -0800; -08:00
U	Microsecond	Number	698

See also

• to_timestamp
• to_date
• to_str