14 KiB
Functions for working with dates and times
Support for time zones
All functions for working with the date and time that have a logical use for the time zone can accept a second optional time zone argument. Example: Asia/Yekaterinburg. In this case, they use the specified time zone instead of the local (default) one.
SELECT
toDateTime('2016-06-15 23:00:00') AS time,
toDate(time) AS date_local,
toDate(time, 'Asia/Yekaterinburg') AS date_yekat,
toString(time, 'US/Samoa') AS time_samoa
┌────────────────time─┬─date_local─┬─date_yekat─┬─time_samoa──────────┐
│ 2016-06-15 23:00:00 │ 2016-06-15 │ 2016-06-16 │ 2016-06-15 09:00:00 │
└─────────────────────┴────────────┴────────────┴─────────────────────┘
Only time zones that differ from UTC by a whole number of hours are supported.
toTimeZone
Convert time or date and time to the specified time zone.
toYear
Converts a date or date with time to a UInt16 number containing the year number (AD).
toQuarter
Converts a date or date with time to a UInt8 number containing the quarter number.
toMonth
Converts a date or date with time to a UInt8 number containing the month number (1-12).
toDayOfYear
Converts a date or date with time to a UInt16 number containing the number of the day of the year (1-366).
toDayOfMonth
Converts a date or date with time to a UInt8 number containing the number of the day of the month (1-31).
toDayOfWeek
Converts a date or date with time to a UInt8 number containing the number of the day of the week (Monday is 1, and Sunday is 7).
toHour
Converts a date with time to a UInt8 number containing the number of the hour in 24-hour time (0-23). This function assumes that if clocks are moved ahead, it is by one hour and occurs at 2 a.m., and if clocks are moved back, it is by one hour and occurs at 3 a.m. (which is not always true – even in Moscow the clocks were twice changed at a different time).
toMinute
Converts a date with time to a UInt8 number containing the number of the minute of the hour (0-59).
toSecond
Converts a date with time to a UInt8 number containing the number of the second in the minute (0-59). Leap seconds are not accounted for.
toUnixTimestamp
Converts a date with time to a unix timestamp.
toStartOfYear
Rounds down a date or date with time to the first day of the year. Returns the date.
toStartOfISOYear
Rounds down a date or date with time to the first day of ISO year. Returns the date.
toStartOfQuarter
Rounds down a date or date with time to the first day of the quarter. The first day of the quarter is either 1 January, 1 April, 1 July, or 1 October. Returns the date.
toStartOfMonth
Rounds down a date or date with time to the first day of the month. Returns the date.
!!! attention The behavior of parsing incorrect dates is implementation specific. ClickHouse may return zero date, throw an exception or do "natural" overflow.
toMonday
Rounds down a date or date with time to the nearest Monday. Returns the date.
toStartOfWeek(t[,mode])
Rounds down a date or date with time to the nearest Sunday or Monday by mode. Returns the date. The mode argument works exactly like the mode argument to toWeek(). For the single-argument syntax, a mode value of 0 is used.
toStartOfDay
Rounds down a date with time to the start of the day.
toStartOfHour
Rounds down a date with time to the start of the hour.
toStartOfMinute
Rounds down a date with time to the start of the minute.
toStartOfFiveMinute
Rounds down a date with time to the start of the five-minute interval.
toStartOfTenMinutes
Rounds down a date with time to the start of the ten-minute interval.
toStartOfFifteenMinutes
Rounds down the date with time to the start of the fifteen-minute interval.
toStartOfInterval(time_or_data, INTERVAL x unit [, time_zone])
This is a generalization of other functions named toStartOf*. For example,
toStartOfInterval(t, INTERVAL 1 year) returns the same as toStartOfYear(t),
toStartOfInterval(t, INTERVAL 1 month) returns the same as toStartOfMonth(t),
toStartOfInterval(t, INTERVAL 1 day) returns the same as toStartOfDay(t),
toStartOfInterval(t, INTERVAL 15 minute) returns the same as toStartOfFifteenMinutes(t) etc.
toTime
Converts a date with time to a certain fixed date, while preserving the time.
toRelativeYearNum
Converts a date with time or date to the number of the year, starting from a certain fixed point in the past.
toRelativeQuarterNum
Converts a date with time or date to the number of the quarter, starting from a certain fixed point in the past.
toRelativeMonthNum
Converts a date with time or date to the number of the month, starting from a certain fixed point in the past.
toRelativeWeekNum
Converts a date with time or date to the number of the week, starting from a certain fixed point in the past.
toRelativeDayNum
Converts a date with time or date to the number of the day, starting from a certain fixed point in the past.
toRelativeHourNum
Converts a date with time or date to the number of the hour, starting from a certain fixed point in the past.
toRelativeMinuteNum
Converts a date with time or date to the number of the minute, starting from a certain fixed point in the past.
toRelativeSecondNum
Converts a date with time or date to the number of the second, starting from a certain fixed point in the past.
toISOYear
Converts a date or date with time to a UInt16 number containing the ISO Year number.
toISOWeek
Converts a date or date with time to a UInt8 number containing the ISO Week number.
toWeek(date[,mode])
This function returns the week number for date or datetime. The two-argument form of toWeek() enables you to specify whether the week starts on Sunday or Monday and whether the return value should be in the range from 0 to 53 or from 1 to 53. If the mode argument is omitted, the default mode is 0.
toISOWeek() is a compatibility function that is equivalent to toWeek(date,3).
The following table describes how the mode argument works.
| Mode | First day of week | Range | Week 1 is the first week … |
|---|---|---|---|
| 0 | Sunday | 0-53 | with a Sunday in this year |
| 1 | Monday | 0-53 | with 4 or more days this year |
| 2 | Sunday | 1-53 | with a Sunday in this year |
| 3 | Monday | 1-53 | with 4 or more days this year |
| 4 | Sunday | 0-53 | with 4 or more days this year |
| 5 | Monday | 0-53 | with a Monday in this year |
| 6 | Sunday | 1-53 | with 4 or more days this year |
| 7 | Monday | 1-53 | with a Monday in this year |
| 8 | Sunday | 1-53 | contains January 1 |
| 9 | Monday | 1-53 | contains January 1 |
For mode values with a meaning of “with 4 or more days this year,” weeks are numbered according to ISO 8601:1988:
-
If the week containing January 1 has 4 or more days in the new year, it is week 1.
-
Otherwise, it is the last week of the previous year, and the next week is week 1.
For mode values with a meaning of “contains January 1”, the week contains January 1 is week 1. It doesn't matter how many days in the new year the week contained, even if it contained only one day.
toWeek(date, [, mode][, Timezone])
Parameters
date– Date or DateTime.mode– Optional parameter, Range of values is [0,9], default is 0.Timezone– Optional parameter, it behaves like any other conversion function.
Example
SELECT toDate('2016-12-27') AS date, toWeek(date) AS week0, toWeek(date,1) AS week1, toWeek(date,9) AS week9;
┌───────date─┬─week0─┬─week1─┬─week9─┐
│ 2016-12-27 │ 52 │ 52 │ 1 │
└────────────┴───────┴───────┴───────┘
toYearWeek(date[,mode])
Returns year and week for a date. The year in the result may be different from the year in the date argument for the first and the last week of the year.
The mode argument works exactly like the mode argument to toWeek(). For the single-argument syntax, a mode value of 0 is used.
toISOYear() is a compatibility function that is equivalent to intDiv(toYearWeek(date,3),100).
Example
SELECT toDate('2016-12-27') AS date, toYearWeek(date) AS yearWeek0, toYearWeek(date,1) AS yearWeek1, toYearWeek(date,9) AS yearWeek9;
┌───────date─┬─yearWeek0─┬─yearWeek1─┬─yearWeek9─┐
│ 2016-12-27 │ 201652 │ 201652 │ 201701 │
└────────────┴───────────┴───────────┴───────────┘
now
Accepts zero arguments and returns the current time at one of the moments of request execution. This function returns a constant, even if the request took a long time to complete.
today
Accepts zero arguments and returns the current date at one of the moments of request execution. The same as 'toDate(now())'.
yesterday
Accepts zero arguments and returns yesterday's date at one of the moments of request execution. The same as 'today() - 1'.
timeSlot
Rounds the time to the half hour. This function is specific to Yandex.Metrica, since half an hour is the minimum amount of time for breaking a session into two sessions if a tracking tag shows a single user's consecutive pageviews that differ in time by strictly more than this amount. This means that tuples (the tag ID, user ID, and time slot) can be used to search for pageviews that are included in the corresponding session.
toYYYYMM
Converts a date or date with time to a UInt32 number containing the year and month number (YYYY * 100 + MM).
toYYYYMMDD
Converts a date or date with time to a UInt32 number containing the year and month number (YYYY * 10000 + MM * 100 + DD).
toYYYYMMDDhhmmss
Converts a date or date with time to a UInt64 number containing the year and month number (YYYY * 10000000000 + MM * 100000000 + DD * 1000000 + hh * 10000 + mm * 100 + ss).
addYears, addMonths, addWeeks, addDays, addHours, addMinutes, addSeconds, addQuarters
Function adds a Date/DateTime interval to a Date/DateTime and then return the Date/DateTime. For example:
WITH
toDate('2018-01-01') AS date,
toDateTime('2018-01-01 00:00:00') AS date_time
SELECT
addYears(date, 1) AS add_years_with_date,
addYears(date_time, 1) AS add_years_with_date_time
┌─add_years_with_date─┬─add_years_with_date_time─┐
│ 2019-01-01 │ 2019-01-01 00:00:00 │
└─────────────────────┴──────────────────────────┘
subtractYears, subtractMonths, subtractWeeks, subtractDays, subtractHours, subtractMinutes, subtractSeconds, subtractQuarters
Function subtract a Date/DateTime interval to a Date/DateTime and then return the Date/DateTime. For example:
WITH
toDate('2019-01-01') AS date,
toDateTime('2019-01-01 00:00:00') AS date_time
SELECT
subtractYears(date, 1) AS subtract_years_with_date,
subtractYears(date_time, 1) AS subtract_years_with_date_time
┌─subtract_years_with_date─┬─subtract_years_with_date_time─┐
│ 2018-01-01 │ 2018-01-01 00:00:00 │
└──────────────────────────┴───────────────────────────────┘
dateDiff('unit', t1, t2, [timezone])
Return the difference between two times expressed in 'unit' e.g. 'hours'. 't1' and 't2' can be Date or DateTime, If 'timezone' is specified, it applied to both arguments. If not, timezones from datatypes 't1' and 't2' are used. If that timezones are not the same, the result is unspecified.
Supported unit values:
| unit |
|---|
| second |
| minute |
| hour |
| day |
| week |
| month |
| quarter |
| year |
timeSlots(StartTime, Duration,[, Size])
For a time interval starting at 'StartTime' and continuing for 'Duration' seconds, it returns an array of moments in time, consisting of points from this interval rounded down to the 'Size' in seconds. 'Size' is an optional parameter: a constant UInt32, set to 1800 by default.
For example, timeSlots(toDateTime('2012-01-01 12:20:00'), 600) = [toDateTime('2012-01-01 12:00:00'), toDateTime('2012-01-01 12:30:00')].
This is necessary for searching for pageviews in the corresponding session.
formatDateTime(Time, Format[, Timezone])
Function formats a Time according given Format string. N.B.: Format is a constant expression, e.g. you can not have multiple formats for single result column.
Supported modifiers for Format:
("Example" column shows formatting result for time 2018-01-02 22:33:44)
| Modifier | Description | Example |
|---|---|---|
| %C | year divided by 100 and truncated to integer (00-99) | 20 |
| %d | day of the month, zero-padded (01-31) | 02 |
| %D | Short MM/DD/YY date, equivalent to %m/%d/%y | 01/02/18 |
| %e | day of the month, space-padded ( 1-31) | 2 |
| %F | short YYYY-MM-DD date, equivalent to %Y-%m-%d | 2018-01-02 |
| %H | hour in 24h format (00-23) | 22 |
| %I | hour in 12h format (01-12) | 10 |
| %j | day of the year (001-366) | 002 |
| %m | month as a decimal number (01-12) | 01 |
| %M | minute (00-59) | 33 |
| %n | new-line character ('\n') | |
| %p | AM or PM designation | PM |
| %R | 24-hour HH:MM time, equivalent to %H:%M | 22:33 |
| %S | second (00-59) | 44 |
| %t | horizontal-tab character ('\t') | |
| %T | ISO 8601 time format (HH:MM:SS), equivalent to %H:%M:%S | 22:33:44 |
| %u | ISO 8601 weekday as number with Monday as 1 (1-7) | 2 |
| %V | ISO 8601 week number (01-53) | 01 |
| %w | weekday as a decimal number with Sunday as 0 (0-6) | 2 |
| %y | Year, last two digits (00-99) | 18 |
| %Y | Year | 2018 |
| %% | a % sign | % |