What are the sqlite equivalents of INTERVAL and UTC_TIMESTAMP? For example, imagine you were "porting" the following SQL from MySQL to sqlite:
SELECT mumble
FROM blah
WHERE blah.heart_beat_time > utc_timestamp() - INTERVAL 600 SECOND;
datetime('now') provides you the current date and time in UTC, so is the SQLite equivalent of MySQL's UTC_TIMESTAMP().
It may also be useful to know that given a date and time string, datetime can convert it from localtime into UTC, using datetime('2011-09-25 18:18', 'utc').
You can also use the datetime() function to apply modifiers such as '+1 day', 'start of month', '- 10 years' and many more.
Therefore, your example would look like this in SQLite:
SELECT mumble
FROM blah
WHERE blah.heart_beat_time > datetime('now', '-600 seconds');
You can find more of the modifiers on the SQLite Date and Time Functions page.
There's no native timestamp support in sqlite.
I've used plain old (64-bit) integers as timestamps, representing either micro- or milliseconds since an epoch.
Therefore, assuming milliseconds:
SELECT mumble
FROM blah
WHERE blah.heart_beat_time_millis > ? - 600*1000;
and bind system time in milliseconds to the first param.
there is LOCAL_TIMESTAMP in SQLite, but it's GMT.
Related
I have a table with timestamp column and the values stored in timestamp column are like
20180608T002304.507Z , 20180608T001745.821Z, 20180608T001628.170Z, 20180608T001336.516Z
I would like to get timestamp in "YYYY-MM-dd" formate.
Used strftime() function , but no use
when I query strftime('%Y-%m-%d %H:%M', timestamp) getting null
Thanks in advance
This is not one of the supported time string formats. Change the values so that they contain the appropriate punctuation:
sqlite> SELECT date('20180608T002304.507Z');
sqlite> SELECT date('2018-06-08T00:23:04.507Z');
2018-06-08
Your issue is that strftime along with all the SQLite date functions require specific formats as listed below. 20180608T002304.507Z is not one of the formats, hence the null.
Note the following is based upon your query using strftime('%Y-%m-%d %H:%M', timestamp) as opposed to I would like to get timestamp in "YYYY-MM-dd" formate.
You have two options.
1. You could utilise the substr function e.g.
:-
substr(mytimestamp,1,4)||'-'||
substr(mytimestamp,5,2)||'-'||
substr(mytimestamp,7,2)||' ' ||
substr(mytimestamp,10,2)||':'||
substr(mytimestamp,12,2)
where mytimestamp is the column name
As an example, the following :-
DROP TABLE IF EXISTS mytable;
CREATE TABLE IF NOT EXISTS mytable (mytimestamp);
INSERT INTO mytable VALUES('20180608T002304.507Z'),('20180608T001745.821Z'),('20180608T001628.170Z'),('20180608T001336.516Z');
SELECT
substr(mytimestamp,1,4)||'-'||
substr(mytimestamp,5,2)||'-'||
substr(mytimestamp,7,2)||' ' ||
substr(mytimestamp,10,2)||':'||
substr(mytimestamp,12,2)
FROM mytable;
results in :-
2. Alter the source data to match one of the acceptable/recognised formats.
This could be done using something based upon :-
UPDATE mytable SET mytimestamp =
substr(mytimestamp,1,4)||'-'|| -- Year
substr(mytimestamp,5,2)||'-'|| -- Month
substr(mytimestamp,7,2)|| -- Day
substr(mytimestamp,9,1)|| -- T (or space)
substr(mytimestamp,10,2)||':'||
substr(mytimestamp,12,2)||':'||
substr(mytimestamp,14)
;
This based upon the table that was created above.
After running the update then using :-
SELECT strftime('%Y-%m-%d %H:%M', mytimestamp) FROM mytable;
results in :-
Time Strings A time string can be in any of the following formats:
YYYY-MM-DD
YYYY-MM-DD HH:MM
YYYY-MM-DD HH:MM:SS
YYYY-MM-DD HH:MM:SS.SSS
YYYY-MM-DDTHH:MM
YYYY-MM-DDTHH:MM:SS
YYYY-MM-DDTHH:MM:SS.SSS
HH:MM
HH:MM:SS
HH:MM:SS.SSS
now
DDDDDDDDDD
In formats 5 through 7, the "T" is a literal character separating the
date and the time, as required by ISO-8601. Formats 8 through 10 that
specify only a time assume a date of 2000-01-01. Format 11, the string
'now', is converted into the current date and time as obtained from
the xCurrentTime method of the sqlite3_vfs object in use. The 'now'
argument to date and time functions always returns exactly the same
value for multiple invocations within the same sqlite3_step() call.
Universal Coordinated Time (UTC) is used. Format 12 is the Julian day
number expressed as a floating point value.
Formats 2 through 10 may be optionally followed by a timezone
indicator of the form "[+-]HH:MM" or just "Z". The date and time
functions use UTC or "zulu" time internally, and so the "Z" suffix is
a no-op. Any non-zero "HH:MM" suffix is subtracted from the indicated
date and time in order to compute zulu time. For example, all of the
following time strings are equivalent:
2013-10-07 08:23:19.120
2013-10-07T08:23:19.120Z
2013-10-07 04:23:19.120-04:00
2456572.84952685
In formats 4, 7, and 10, the fractional seconds value SS.SSS can have
one or more digits following the decimal point. Exactly three digits
are shown in the examples because only the first three digits are
significant to the result, but the input string can have fewer or more
than three digits and the date/time functions will still operate
correctly. Similarly, format 12 is shown with 10 significant digits,
but the date/time functions will really accept as many or as few
digits as are necessary to represent the Julian day number.
SQL As Understood By SQLite - Date And Time Functions
I have a column in my SQLite database that stores time values in UTC. How do i get the count of distinct days?
The below gives a result based on the UTC days, which would be wrong in the local timezone :
select distinct(date(column)) from table
The below would consider the time as well, which would be wrong :
select distinct(datetime(column,'localtime')) from table
Would it make sense to convert the date to localtime as below :
select distinct(date(column,'localtime')) from table
I am not sure if using the localtime conversion on a date, as opposed to a datetime, has any effect.
The only difference between date and datetime is in the output format, not in any internal calculations.
(All five date/time functions behave the same in this regard.)
I want to make a query to get records between specified hours. For example, i want to get all records between 00:00 and 01:00 for all days. So, the date does not matter but hours. How to do that?
I have done this, but it only return for certain dates.
Select name from my_table where date_column> beginning and date_column< end
Here beginning and end are in millisecond. Also my date_column is stored in millisecond format.
Use strftime():
Select name
from my_table
where strftime('%H', date_column) = '00';
This just checks the hour. You could use '%H:%M:%S' if you wanted more granularity.
EDIT:
You do not have a date time value. You have something else. It looks like a Unix epoch time measured in milliseconds rather than seconds. If so, the following should work:
Select name, datetime(date_column/1000, 'unixepoch')
from my_table
where strftime('%H', datetime(date_column/1000, 'unixepoch')) = '19';
However, none of the times are at hour 3. You may need to convert using your localtime.
I have this query which works in SQL server:
Convert(datetime, [ChangedDate]) >= DATEADD(DAY, -3, CAST(GETDATE() AS DATE))
I want to make it work in Android SQLite database.
As far as I understood I need to use something like: date('now','+14 day') instead of DATEADD, but it gives me an error on datetime (it could be here Convert(datetime,...) in sqlite.
Can you modify this query in order to make it works on SQLite?
SQLite does not have a date data type. So you're not required to use convert or cast. A query like this would work:
select *
from table1
where col1 < datetime('now', '-3 days')
Example at SQL Fiddle.
For more details, see the SQLite manual:
1.2 Date and Time Datatype
SQLite does not have a storage class set aside for storing dates
and/or times. Instead, the built-in Date And Time Functions of SQLite
are capable of storing dates and times as TEXT, REAL, or INTEGER
values:
TEXT as ISO8601 strings ("YYYY-MM-DD HH:MM:SS.SSS").
REAL as Julian
day numbers, the number of days since noon in Greenwich on November
24, 4714 B.C. according to the proleptic Gregorian calendar.
INTEGER
as Unix Time, the number of seconds since 1970-01-01 00:00:00 UTC.
Applications can chose to store dates and times in any of these
formats and freely convert between formats using the built-in date and
time functions.
I have a sqlite database. I have three columns:_id, date, value.
I now want to extract a count of the _id:s depending on the day in the date, and calculate an average of the int value. This is for an Android app.
So I want to "select the day in date and for each day ( for sixty days), count how many _id:s there are for this day. Finally calculate the average of value.
I guess it is something like :
"SELECT DATE('now' 'days[i]') as date, COUNT(_id) as count, AVG(value) as vl FROM v_efforts WHERE DATE(v_efforts.date) = DATE('now' 'days[i]')";
But I can't get the 'days[i]' to work. I don't know how i can get this value to increase to sixty, and then how I can store the count and vl for each of these sixty days.
THanks a lot!
You'll want to use a GROUP BY expression to aggregate the entries by date. It's not quite clear whether you're looking for the last 60 days of entries in the database, or the entries from the last 60 real days (which would only be the same if you can assume that there are entries every day).
For the former (last 60 days which had database entries), you can use a LIMIT clause:
SELECT date,COUNT(_id),AVG(value) FROM v_efforts GROUP BY date ORDER BY date DESC LIMIT 60;
For the latter (last 60 real days), you can use WHERE:
SELECT date,COUNT(_id),AVG(value) FROM v_efforts WHERE date>DATE('now','-60 days') GROUP BY date ORDER BY date DESC;
The docs for Version 3 are pretty decent:
http://www.sqlite.org/lang_datefunc.html
I would look at the block that deals with the built in date time functions. Since SQLite doesn't support an actual date datetype:
Compute the current date:
SELECT date('now');
Compute the last day of the current month:
SELECT date('now','start of month','+1
month','-1 day');
Compute the date and time given a unix timestamp 1092941466.
SELECT datetime(1092941466,
'unixepoch');
Compute the date and time given a unix timestamp 1092941466, and compensate for your local timezone.
SELECT datetime(1092941466,
'unixepoch', 'localtime');
Compute the current unix timestamp.
SELECT strftime('%s','now');
Compute the number of days since the signing of the US Declaration of Independence.
SELECT julianday('now') -
julianday('1776-07-04');
Compute the number of seconds since a particular moment in 2004:
SELECT strftime('%s','now') -
strftime('%s','2004-01-01 02:34:56');
Compute the date of the first Tuesday in October for the current year.
SELECT date('now','start of year','+9
months','weekday 2');
Compute the time since the unix epoch in seconds (like strftime('%s','now') except includes fractional part):
SELECT (julianday('now') -
2440587.5)*86400.0;