ClickHouse/docs/en/query_language/functions/date_time_functions.md

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# Functions for working with dates and times
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Support for time zones
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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.
CLICKHOUSE-2720: progress on website (#865) * update presentations * CLICKHOUSE-2936: redirect from clickhouse.yandex.ru and clickhouse.yandex.com * update submodule * lost files * CLICKHOUSE-2981: prefer sphinx docs over original reference * CLICKHOUSE-2981: docs styles more similar to main website + add flags to switch language links * update presentations * Less confusing directory structure (docs -> doc/reference/) * Minify sphinx docs too * Website release script: fail fast + pass docker hash on deploy * Do not underline links in docs * shorter * cleanup docker images * tune nginx config * CLICKHOUSE-3043: get rid of habrastorage links * Lost translation * CLICKHOUSE-2936: temporary client-side redirect * behaves weird in test * put redirect back * CLICKHOUSE-3047: copy docs txts to public too * move to proper file * remove old pages to avoid confusion * Remove reference redirect warning for now * Refresh README.md * Yellow buttons in docs * Use svg flags instead of unicode ones in docs * fix test website instance * Put flags to separate files * wrong flag * Copy Yandex.Metrica introduction from main page to docs * Yet another home page structure change, couple new blocks (CLICKHOUSE-3045) * Update Contacts section * CLICKHOUSE-2849: more detailed legal information * CLICKHOUSE-2978 preparation - split by files * More changes in Contacts block * Tune texts on index page * update presentations * One more benchmark * Add usage sections to index page, adapted from slides * Get the roadmap started, based on slides from last ClickHouse Meetup * CLICKHOUSE-2977: some rendering tuning * Get rid of excessive section in the end of getting started * Make headers linkable * CLICKHOUSE-2981: links to editing reference - https://github.com/yandex/ClickHouse/issues/849 * CLICKHOUSE-2981: fix mobile styles in docs * Ban crawling of duplicating docs * Open some external links in new tab * Ban old docs too * Lots of trivial fixes in english docs * Lots of trivial fixes in russian docs * Remove getting started copies in markdown * Add Yandex.Webmaster * Fix some sphinx warnings * More warnings fixed in english docs * More sphinx warnings fixed * Add code-block:: text * More code-block:: text * These headers look not that well * Better switch between documentation languages * merge use_case.rst into ya_metrika_task.rst * Edit the agg_functions.rst texts * Add lost empty lines
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``` sql
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
```
CLICKHOUSE-2720: progress on website and reference (#886) * update presentations * CLICKHOUSE-2936: redirect from clickhouse.yandex.ru and clickhouse.yandex.com * update submodule * lost files * CLICKHOUSE-2981: prefer sphinx docs over original reference * CLICKHOUSE-2981: docs styles more similar to main website + add flags to switch language links * update presentations * Less confusing directory structure (docs -> doc/reference/) * Minify sphinx docs too * Website release script: fail fast + pass docker hash on deploy * Do not underline links in docs * shorter * cleanup docker images * tune nginx config * CLICKHOUSE-3043: get rid of habrastorage links * Lost translation * CLICKHOUSE-2936: temporary client-side redirect * behaves weird in test * put redirect back * CLICKHOUSE-3047: copy docs txts to public too * move to proper file * remove old pages to avoid confusion * Remove reference redirect warning for now * Refresh README.md * Yellow buttons in docs * Use svg flags instead of unicode ones in docs * fix test website instance * Put flags to separate files * wrong flag * Copy Yandex.Metrica introduction from main page to docs * Yet another home page structure change, couple new blocks (CLICKHOUSE-3045) * Update Contacts section * CLICKHOUSE-2849: more detailed legal information * CLICKHOUSE-2978 preparation - split by files * More changes in Contacts block * Tune texts on index page * update presentations * One more benchmark * Add usage sections to index page, adapted from slides * Get the roadmap started, based on slides from last ClickHouse Meetup * CLICKHOUSE-2977: some rendering tuning * Get rid of excessive section in the end of getting started * Make headers linkable * CLICKHOUSE-2981: links to editing reference - https://github.com/yandex/ClickHouse/issues/849 * CLICKHOUSE-2981: fix mobile styles in docs * Ban crawling of duplicating docs * Open some external links in new tab * Ban old docs too * Lots of trivial fixes in english docs * Lots of trivial fixes in russian docs * Remove getting started copies in markdown * Add Yandex.Webmaster * Fix some sphinx warnings * More warnings fixed in english docs * More sphinx warnings fixed * Add code-block:: text * More code-block:: text * These headers look not that well * Better switch between documentation languages * merge use_case.rst into ya_metrika_task.rst * Edit the agg_functions.rst texts * Add lost empty lines * Lost blank lines * Add new logo sizes * update presentations * Next step in migrating to new documentation * Fix all warnings in en reference * Fix all warnings in ru reference * Re-arrange existing reference * Move operation tips to main reference * Fix typos noticed by milovidov@ * Get rid of zookeeper.md * Looks like duplicate of tutorial.html * Fix some mess with html tags in tutorial * No idea why nobody noticed this before, but it was completely not clear whet to get the data * Match code block styling between main and tutorial pages (in favor of the latter) * Get rid of some copypaste in tutorial * Normalize header styles * Move example_datasets to sphinx * Move presentations submodule to website * Move and update README.md * No point in duplicating articles from habrahabr here * Move development-related docs as is for now * doc/reference/ -> docs/ (to match the URL on website) * Adapt links to match the previous commit * Adapt development docs to rst (still lacks translation and strikethrough support) * clean on release * blacklist presentations in gulp * strikethrough support in sphinx * just copy development folder for now * fix weird introduction in style article * Style guide translation (WIP) * Finish style guide translation to English * gulp clean separately * Update year in LICENSE * Initial CONTRIBUTING.md * Fix remaining links to old docs in tutorial * Some tutorial fixes * Typo * Another typo * Update list of authors from yandex-team accoding to git log
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```
┌────────────────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 │
└─────────────────────┴────────────┴────────────┴─────────────────────┘
```
CLICKHOUSE-2720: progress on website (#865) * update presentations * CLICKHOUSE-2936: redirect from clickhouse.yandex.ru and clickhouse.yandex.com * update submodule * lost files * CLICKHOUSE-2981: prefer sphinx docs over original reference * CLICKHOUSE-2981: docs styles more similar to main website + add flags to switch language links * update presentations * Less confusing directory structure (docs -> doc/reference/) * Minify sphinx docs too * Website release script: fail fast + pass docker hash on deploy * Do not underline links in docs * shorter * cleanup docker images * tune nginx config * CLICKHOUSE-3043: get rid of habrastorage links * Lost translation * CLICKHOUSE-2936: temporary client-side redirect * behaves weird in test * put redirect back * CLICKHOUSE-3047: copy docs txts to public too * move to proper file * remove old pages to avoid confusion * Remove reference redirect warning for now * Refresh README.md * Yellow buttons in docs * Use svg flags instead of unicode ones in docs * fix test website instance * Put flags to separate files * wrong flag * Copy Yandex.Metrica introduction from main page to docs * Yet another home page structure change, couple new blocks (CLICKHOUSE-3045) * Update Contacts section * CLICKHOUSE-2849: more detailed legal information * CLICKHOUSE-2978 preparation - split by files * More changes in Contacts block * Tune texts on index page * update presentations * One more benchmark * Add usage sections to index page, adapted from slides * Get the roadmap started, based on slides from last ClickHouse Meetup * CLICKHOUSE-2977: some rendering tuning * Get rid of excessive section in the end of getting started * Make headers linkable * CLICKHOUSE-2981: links to editing reference - https://github.com/yandex/ClickHouse/issues/849 * CLICKHOUSE-2981: fix mobile styles in docs * Ban crawling of duplicating docs * Open some external links in new tab * Ban old docs too * Lots of trivial fixes in english docs * Lots of trivial fixes in russian docs * Remove getting started copies in markdown * Add Yandex.Webmaster * Fix some sphinx warnings * More warnings fixed in english docs * More sphinx warnings fixed * Add code-block:: text * More code-block:: text * These headers look not that well * Better switch between documentation languages * merge use_case.rst into ya_metrika_task.rst * Edit the agg_functions.rst texts * Add lost empty lines
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Only time zones that differ from UTC by a whole number of hours are supported.
CLICKHOUSE-2720: progress on website (#865) * update presentations * CLICKHOUSE-2936: redirect from clickhouse.yandex.ru and clickhouse.yandex.com * update submodule * lost files * CLICKHOUSE-2981: prefer sphinx docs over original reference * CLICKHOUSE-2981: docs styles more similar to main website + add flags to switch language links * update presentations * Less confusing directory structure (docs -> doc/reference/) * Minify sphinx docs too * Website release script: fail fast + pass docker hash on deploy * Do not underline links in docs * shorter * cleanup docker images * tune nginx config * CLICKHOUSE-3043: get rid of habrastorage links * Lost translation * CLICKHOUSE-2936: temporary client-side redirect * behaves weird in test * put redirect back * CLICKHOUSE-3047: copy docs txts to public too * move to proper file * remove old pages to avoid confusion * Remove reference redirect warning for now * Refresh README.md * Yellow buttons in docs * Use svg flags instead of unicode ones in docs * fix test website instance * Put flags to separate files * wrong flag * Copy Yandex.Metrica introduction from main page to docs * Yet another home page structure change, couple new blocks (CLICKHOUSE-3045) * Update Contacts section * CLICKHOUSE-2849: more detailed legal information * CLICKHOUSE-2978 preparation - split by files * More changes in Contacts block * Tune texts on index page * update presentations * One more benchmark * Add usage sections to index page, adapted from slides * Get the roadmap started, based on slides from last ClickHouse Meetup * CLICKHOUSE-2977: some rendering tuning * Get rid of excessive section in the end of getting started * Make headers linkable * CLICKHOUSE-2981: links to editing reference - https://github.com/yandex/ClickHouse/issues/849 * CLICKHOUSE-2981: fix mobile styles in docs * Ban crawling of duplicating docs * Open some external links in new tab * Ban old docs too * Lots of trivial fixes in english docs * Lots of trivial fixes in russian docs * Remove getting started copies in markdown * Add Yandex.Webmaster * Fix some sphinx warnings * More warnings fixed in english docs * More sphinx warnings fixed * Add code-block:: text * More code-block:: text * These headers look not that well * Better switch between documentation languages * merge use_case.rst into ya_metrika_task.rst * Edit the agg_functions.rst texts * Add lost empty lines
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## toTimeZone
Convert time or date and time to the specified time zone.
## toYear
CLICKHOUSE-2720: progress on website (#865) * update presentations * CLICKHOUSE-2936: redirect from clickhouse.yandex.ru and clickhouse.yandex.com * update submodule * lost files * CLICKHOUSE-2981: prefer sphinx docs over original reference * CLICKHOUSE-2981: docs styles more similar to main website + add flags to switch language links * update presentations * Less confusing directory structure (docs -> doc/reference/) * Minify sphinx docs too * Website release script: fail fast + pass docker hash on deploy * Do not underline links in docs * shorter * cleanup docker images * tune nginx config * CLICKHOUSE-3043: get rid of habrastorage links * Lost translation * CLICKHOUSE-2936: temporary client-side redirect * behaves weird in test * put redirect back * CLICKHOUSE-3047: copy docs txts to public too * move to proper file * remove old pages to avoid confusion * Remove reference redirect warning for now * Refresh README.md * Yellow buttons in docs * Use svg flags instead of unicode ones in docs * fix test website instance * Put flags to separate files * wrong flag * Copy Yandex.Metrica introduction from main page to docs * Yet another home page structure change, couple new blocks (CLICKHOUSE-3045) * Update Contacts section * CLICKHOUSE-2849: more detailed legal information * CLICKHOUSE-2978 preparation - split by files * More changes in Contacts block * Tune texts on index page * update presentations * One more benchmark * Add usage sections to index page, adapted from slides * Get the roadmap started, based on slides from last ClickHouse Meetup * CLICKHOUSE-2977: some rendering tuning * Get rid of excessive section in the end of getting started * Make headers linkable * CLICKHOUSE-2981: links to editing reference - https://github.com/yandex/ClickHouse/issues/849 * CLICKHOUSE-2981: fix mobile styles in docs * Ban crawling of duplicating docs * Open some external links in new tab * Ban old docs too * Lots of trivial fixes in english docs * Lots of trivial fixes in russian docs * Remove getting started copies in markdown * Add Yandex.Webmaster * Fix some sphinx warnings * More warnings fixed in english docs * More sphinx warnings fixed * Add code-block:: text * More code-block:: text * These headers look not that well * Better switch between documentation languages * merge use_case.rst into ya_metrika_task.rst * Edit the agg_functions.rst texts * Add lost empty lines
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Converts a date or date with time to a UInt16 number containing the year number (AD).
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## toQuarter
Converts a date or date with time to a UInt8 number containing the quarter number.
## toMonth
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Converts a date or date with time to a UInt8 number containing the month number (1-12).
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## toDayOfYear
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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
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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).
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## toHour
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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
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Converts a date with time to a UInt8 number containing the number of the minute of the hour (0-59).
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## toSecond
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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
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Rounds down a date or date with time to the first day of the year.
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Returns the date.
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## 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
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Rounds down a date or date with time to the first day of the month.
Returns the date.
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!!! 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.
## toStartOfDay
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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.
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## toStartOfMinute
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Rounds down a date with time to the start of the minute.
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## toStartOfFiveMinute
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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.
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## toStartOfFifteenMinutes
Rounds down the date with time to the start of the fifteen-minute interval.
## toStartOfInterval(time_or_data, INTERVAL x unit [, time_zone])
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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.
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## toTime
Converts a date with time to a certain fixed date, while preserving the time.
## toRelativeYearNum
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Converts a date with time or date to the number of the year, starting from a certain fixed point in the past.
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## toRelativeQuarterNum
Converts a date with time or date to the number of the quarter, starting from a certain fixed point in the past.
## toRelativeMonthNum
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Converts a date with time or date to the number of the month, starting from a certain fixed point in the past.
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## toRelativeWeekNum
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Converts a date with time or date to the number of the week, starting from a certain fixed point in the past.
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## toRelativeDayNum
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Converts a date with time or date to the number of the day, starting from a certain fixed point in the past.
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## toRelativeHourNum
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Converts a date with time or date to the number of the hour, starting from a certain fixed point in the past.
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## toRelativeMinuteNum
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Converts a date with time or date to the number of the minute, starting from a certain fixed point in the past.
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## toRelativeSecondNum
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Converts a date with time or date to the number of the second, starting from a certain fixed point in the past.
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## 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.
## now
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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.
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## today
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Accepts zero arguments and returns the current date at one of the moments of request execution.
The same as 'toDate(now())'.
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## yesterday
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Accepts zero arguments and returns yesterday's date at one of the moments of request execution.
The same as 'today() - 1'.
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## timeSlot
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Rounds the time to the half hour.
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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.
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## 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:
```sql
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:
```sql
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:
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| 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|01/02/2018|
|%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|%|
[Original article](https://clickhouse.yandex/docs/en/query_language/functions/date_time_functions/) <!--hide-->