1. Taming The Snowflake DATE & TIMESTAMP Data
Manipulation & Arithmetic
(Faysal Shaarani)
Date and Time calculations are among the most widely used and most critical
computations in Analytics and Data Mining. The objective of this document is to
make your experience with Dates and Timestamps in Snowflake a smooth and
simple one.
Snowflake supports DATE and TIMESTAMP data types:
1. DATE: The DATE type stores dates (without time). Accepts dates in the
most common forms such as YYYY-MM-DD or DD-MON-YYYY etc. All
accepted timestamps are valid inputs for dates as well.
2. TIMESTAMP: Snowflake supports three flavors of the TIMESTAMP type
and a special TIMESTAMP alias. TIMESTAMP type in Snowflake is a
user-defined alias to one of the three types. In all operations where
TIMESTAMP can be used, the specified TIMESTAMP_ flavor will be used
automatically. The actual target type is controlled by
the TIMESTAMP_TYPE_MAPPING configuration option (by default it
is TIMESTAMP_LTZ) and TIMESTAMP type is never stored in the tables.
The timestamp_type_mapping can be set via the following command:
ALTER SESSION SET timestamp_type_
mapping = default;
The three TIMESTAMP types are:
a. TIMESTAMP_LTZ type internally stores UTC time with a specified
precision. All operations are performed in the current session's time
zone, controlled by the TIMEZONE parameter and can be changed
via the ALTER SESSION command:
ALTER SESSION SET
timezone = ‘America/Los_Angeles’;

2. b. TIMESTAMP_NTZ type internally stores "wallclock" time with a
specified precision. All operations are performed without taking any
time zone into account.
c. TIMESTAMP_TZ type internally stores UTC time together with an
associated time zone. When not provided, the session time zone is
used. All operations are performed in the time zone specific for
each record.
The DATE data type in Snowflake contains only date values (without the time
component). The TIMESTAMP data types in Snowflake contain date and time,
and optionally timezone.
Calendar Weeks and Weekdays
In Snowflake, the calendar week starts on Monday, following the ISO-8601
standard. This behavior influences functions like DATEDIFF and DATE_TRUNC.
Also, when extracting the “week” component in functions like DATE_PART and
EXTRACT, ISO week number is returned.
The “dayofweek_iso” component for EXTRACT and DATE_PART follows the
ISO behavior, returning 1 for Monday, 2 for Tuesday, …, 6 for Saturday and 7 for
Sunday. For compatibility with some other systems, the “dayofweek”
component returns 1 for Monday, 2 for Tuesday, …, 6 for Saturday, and 0 for
Sunday (following standard UNIX nomenclature).
Getting Current Date/Time
To get [Today’s Date] as DATE:
select current_date();
2014-08-05
To get [Today’s Date & Time] as TIMESTAMP_LTZ:
select current_timestamp();
Mon, 04 Aug 2014 17:13:02 -0700
Extracting values
To get the [Day of the Week] as number (can be applied to any date or
timestamp):
select extract('dayofweek',current_date())

3. To get the [Name of the Day of the Week] as text (using CURRENT_DATE() as
an example):
This produces short English names, e.g. ‘Sun’, ‘Mon’ etc.
select to_varchar(current_date(), 'DY');
To use arbitrary, explicitly provided weekday names:
select DECODE(
extract ('dayofweek_iso',current_date()),
1, 'Monday',
2, 'Tuesday',
3, 'Wednesday',
4, 'Thursday',
5, 'Friday',
6, 'Saturday',
7, 'Sunday')
Computing Business Calendar:
To get the [First Day of the Current Month ] as DATE
SELECT DATE_TRUNC('month', current_date());
To get the [Last Day of the Current Month] as DATE:
select dateadd('day', -1,
dateadd('month', 1,
date_trunc('month', current_date())));
NOTE: In the above example, date_trunc finds the beginning of the current
month, the following addition of 1 month finds the beginning of the next month,
and final subtraction of 1 day finds the last day in the current month.
To get the [Last Day of the Prior Month] as DATE:
select dateadd(day, -1,
date_trunc('month',current_date()) );
To get the [Month of the Year By Name]:
Simple mode, using English abbreviated month names, e.g. “Jan” and “Dec”
select to_varchar(current_date(), 'Mon');
Using arbitrary, explicitly provided month names:

4. select DECODE extract('month',current_date())
1 , 'January',
2 , 'February',
3 , 'March',
4 , 'April',
5 , 'May',
6 , 'June',
7 , 'July',
8 , 'August',
9 , 'September',
10, 'October',
11, 'November',
12, 'December');
To get the [Date of the Monday of the Current Week]:
select dateadd(day, (extract('dayofweek_iso',
current_date()) * -1) +1 , current_date() );
To get the [Date of the Friday of the Current Week]:
Select dateadd('day', (5 - extract('dayofweek_iso',
current_date()) ), current_date() );
To get the [First Day of the Current Year] as DATE:
select date_trunc('year', current_date());
To get the [First Monday of the Current Month]:
select dateadd(
day,
MOD( 7 + 1 - date_part('dayofweek_iso',
date_trunc('month', current_date()) ), 7),
date_trunc('month', current_date()));
Note: “1” in the “7+1” above results in Monday. Use 2 for Tuesday…7 for
Sunday etc.
To get the [Last Day of the Current Year] as DATE:
select dateadd('day', -1,
dateadd('year', 1,
date_trunc('year', current_date())));
Note: To get the last day of the current month, use "month" instead of "year" on
the above SQL.
To get the [Last Day of the Prior Year] as DATE:
select dateadd('day', -1,
date_trunc('year',current_date()) );

5. To get the [First Day of the Quarter] as DATE:
select date_trunc('quarter',current_date());
To get the [Last Day of the Quarter] as DATE:
select dateadd('day', -1,
dateadd('month', 3,
date_trunc('quarter', current_date())));
To get [Midnight Time (Start of the day) of the Current Day]:
select date_trunc('day', current_timestamp() );
Other Date and Timestamp Operations
To get the [Date or Time Part of today’s Date and Time]:
select date_part(day, current_timestamp());
select date_part(year, current_timestamp());
select date_part(month, current_timestamp());
select date_part(hour, current_timestamp());
select date_part(minute, current_timestamp());
select date_part(second, current_timestamp());
OR
select extract('day', current_timestamp());
select extract('year', current_timestamp());
select extract('month', current_timestamp());
select extract('hour', current_timestamp());
select extract('minute', current_timestamp());
select extract('second', current_timestamp());
OR
select day(current_timestamp() ) ,
hour( current_timestamp() ),
second(current_timestamp()),
minute(current_timestamp()),
month(current_timestamp());
NOTE: Please refer to the table below for additional Date/Time Parts
Masks.
[Date/Time Parts Masks]:
The following table lists different parts of dates and times that can be used by
various functions.

6. Date part or time part Abbreviations
Supported by
functions
Notes
year, years
y, yr, yrs, yy, yyy,
yyyy
extract, date_part,
trunc, date_trunc,
dateadd, datediff
quarter, quarters q, qtr, qtrs trunc, date_trunc
month, months mm, mon, mons
extract, date_part,
trunc, date_trunc,
dateadd, datediff
day, days d, dd
extract, date_part,
trunc, date_trunc,
dateadd, datediff
dayofweek, weekday dow, dw extract, date_part
Values returned are from 0
(Sunday) to 6 (Saturday). Note that
"week" component returns weeks
starting on Monday.
dayofweek_iso,
weekday_iso
dow_iso, dw_iso extract, date_part
Values returned are from 1
(Monday) to 7 (Sunday).
dayofyear, yearday doy, dy extract, date_part
week w, wk
extract, date_part,
date_trunc,
dateadd, datediff,
ISO week (starting on Monday). In
EXTRACT/DATE_PART, the
returned week number
corresponds to ISO 8601 weeks,
where a week belongs to the year
that contains a Thursday of that
week. It means, that the value

7. returned for days in early January
can be 52 or 53 (week belonging to
the previous year), and for days in
late December can be 1 (week
belonging to the next year).
weekofyear, wy, woy extract, date_part See discussion for "week".
hour, hours h, hr, hrs, hh
extract, date_part,
trunc, date_trunc,
dateadd, datediff
minute, minutes m, mi, min, mins
extract, date_part,
trunc, date_trunc,
dateadd, datediff
second, seconds s, sec, secs
extract, date_part,
trunc, date_trunc,
dateadd, datediff
nanosecond,
nanoseconds
ns, nsec, nsecs,
nsecond, nseconds,
nanosec, nanosecs
extract, date_part
timezone_hour tzh extract, date_part
timezone_minute tzm extract, date_part
To add [Different Time Increments to a Date Value]:
select dateadd(year, 2, current_date());
select dateadd(day,2,current_date());
select dateadd(hour,2,current_timestamp());
select dateadd(minute,2,current_timestamp());
select dateadd(second,2,current_timestamp());

8. To [Convert a Valid Character String to a Timestamp]:
select to_timestamp ('12-jan-2013 00:00:00','dd-mon-yyyy
hh:mi:ss');
To [Perform Date Arithmetic on a Valid Date String]:
select dateadd('day',5, to_timestamp ('12-jan-2013
00:00:00','dd-mon-yyyy hh:mi:ss') );
select datediff('day', to_timestamp ('12-jan-2013
00:00:00','dd-mon-yyyy hh:mi:ss') , current_date() );
select datediff('day', to_date ('12-jan-2013 00:00:00','dd-
mon-yyyy hh:mi:ss') , current_date() );
To [Insert a Valid Date String Into a Table with Date Column]:
Create table test (date1 date);
insert into test values (to_date ('12-jan-2013
00:00:00','dd-mon-yyyy hh:mi:ss'));
2013-01-12
insert into test values (to_date ('11:30:40','hh:mi:ss'));
1970-01-01
select to_varchar(date1, 'dd-mon-yyyy hh:mi:ss') from test;
12-Jan-2013 00:00:00
01-Jan-1970 00:00:00
To compute [The Difference Between Two Dates]:
select datediff(year, current_date(),
dateadd(year, 3, current_date() ) );
select datediff(month, current_date(),
dateadd(month, 3, current_date()) );
select datediff(day, current_date(),
dateadd(day, 3, current_date()) );
select datediff(hour, current_timestamp(),
dateadd(hour, 3, current_timestamp()) );
select datediff(minute, current_timestamp(),
dateadd(minute, 3, current_timestamp()) );
select datediff(second, current_timestamp(),
dateadd(second, 3, current_timestamp()) );

9. To create a [Yearly Calendar View in Snowflake]:
create or replace view calendar_2014 as
select n, theDate,
decode (extract('dayofweek',theDate),
1 , 'Monday',
2 , 'Tuesday',
3 , 'Wednesday',
4 , 'Thursday',
5 , 'Friday',
6 , 'Saturday',
0 , 'Sunday'
) theDayOfTheWeek,
decode (extract(month from theDate),
1 , 'January',
2 , 'February',
3 , 'March',
4 , 'April',
5 , 'May',
6 , 'June',
7 , 'July',
8 , 'August',
9 , 'september',
10, 'October',
11, 'November',
12, 'December'
) theMonth,
extract(year from theDate) theYear
from
( select
row_number() over (order by seq4()) as n,
dateadd(day, row_number() over (order by
seq4())-1, to_date('2014-01-01'))
as theDate
from table(generator(rowCount => 365))) order
by n asc;