My table has the below mentioned timestamp
Outcome required: data between 1997 and 1999 morning times i.e. (12:00:01 to 11:59:59)
1997-09-22 18:02:38
1997-10-15 01:26:11
1997-11-03 02:42:40
1997-10-15 01:25:19
1999-10-15 01:25:19
1999-10-15 23:25:19
1998-03-12 20:15:12
1998-02-13 23:52:53
1997-09-23 23:26:01
2000-09-23 23:26:01
I am trying the below query but does not give the right outcome
SELECT * FROM r WHERE ts BETWEEN '1997-01-01 00:00:01' AND '1999-12-31 11:59:59'
I can find the outcome by extracting hours and minutes separately but is there a way where the query is a bit concise?
You need to extract date and time separately to fetch the needed data.
In MySql you can use DATE_FORMAT method to extract same.
Read more here: DATE_FORMAT(date, format)
Your query will be:
SELECT * FROM `r` WHERE DATE_FORMAT(ts, "%Y-%m-%d") BETWEEN '1997-01-01' AND '1999-12-31' AND DATE_FORMAT(date_time, "%H:%i:%s") BETWEEN '00:00:01' AND '11:59:59'
If your date is not in DateTime format then you need to convert your string/raw date to date time format using STR_TO_DATE method.
Read more here: STR_TO_DATE(date, format)
You may use STR_TO_DATE function :
SELECT *
FROM r
WHERE ts >= STR_TO_DATE('1997-01-01', '%Y-%m-%d')
AND ts < STR_TO_DATE('2000-01-01', '%Y-%m-%d')
P.S: ts <= '1999-12-31 11:59:59' implicitly means ts < '2000-01-01'
There's no way to specify particular hours of day within the range comparison that spans years. We'd need to add another predicate (condition) to narrow down the rows that match the range scan.
We can use DATE_FORMAT function to get hours, minutes and seconds (formatted with two digits each)
For example, based on the stated specification (only times between 00:00:01 and 11:59:59) we could add something like this:
AND DATE_FORMAT(r.ts,'%h:%i:%s') BETWEEN '00:00:01' AND '11:59:59'
But it seems really strange to be omitting the second right after midnight, and the second immediately before noon. (MySQL DATETIME can have resolution smaller than a second, up to six decimal digits.)
Personally, I'd identify "morning hours" as simply hour values between 0 and 11, like this:
AND DATE_FORMAT(r.ts,'%h') BETWEEN '00' AND '11'
That will include "morning times" before 12:01 AM and after 11:59 AM. For example, these times would be included by this condition, but be omitted by the first example condition:
00:00:00.555
11:59:59.023
The specification isn't entirely clear... determining whether these times should be included or excluded would help clarify the specification. I suspect the statement of the specification is somewhat jarbled, and we really want all "morning times" between midnight and noon.
SELECT r.*
FROM r
WHERE r.ts >= '1997-01-01'
AND r.ts < '2000-01-01'
AND DATE_FORMAT(r.ts,'%h) BETWEEN '00' AND '11'
But it really depends on the definition of "morning hours", whether that first second after midnight is included or excluded.
Related
This is a question from leetcode, using the second query I got the question wrong but could not identify why
SELECT
user_id,
max(time_stamp) as "last_stamp"
from
logins
where
year(time_stamp) = '2020'
group by
user_id
and
select
user_id,
max(time_stamp) as "last_stamp"
from
logins
where
time_stamp between '2020-01-01' and '2020-12-31'
group by
user_id
The first query uses a function on every row to extract the year (an integer) and compares that to a string. (It would be preferable to use an integer instead.) Whilst this may be sub-optimal, this query would accurately locate all rows that fall into the year 2020.
The second query could fail to locate all rows that fall into 2020. Here it is important to remember that days have a 24 hour duration, and that each day starts at midnight and concludes at midnight 24 hours later. That is; a day does have a start point (midnight) and an end-point (midnight+24 hours).
However a single date used in SQL code cannot be both the start-point and the end-point of the same day, so every date in SQL represents only the start-point. Also note here, that between does NOT magically change the second given date into "the end of that day" - it simply cannot (and does not) do that.
So, when you use time_stamp between '2020-01-01' and '2020-12-31' you need to think of it as meaning "from the start of 2020-01-01 up to and including the start of 2020-12-31". Hence, this excludes the 24 hours duration of 2020-12-31.
The safest way to deal with this is to NOT use between at all, instead write just a few characters more code which will be accurate regardless of the time precision used by any date/datetime/timestamp column:
where
time_stamp >= '2020-01-01' and time_stamp <'2021-01-01'
with the second date being "the start-point of the next day"
See answer to SQL "between" not inclusive
I have a weird problem in mysql!
my query is
SELECT * FROM aa WHERE problemTime>= '2016/03/20' AND problemTime<= '2016/04/20'
the result of this query is nothing , but when I change the first time to 2016/03/19 or 2016/03/21 I have the following result! I mean these queries
SELECT * FROM aa WHERE problemTime>= '2016/03/21' AND problemTime<= '2016/04/20'
or
SELECT * FROM aa WHERE problemTime>= '2016/03/19' AND problemTime<= '2016/04/20'
the result in both time ( 19th and 21th) is
but when I use 20th the result is noting
my main table is
I change the format of time from 2016/03/20 to 2016-03-20 ( I mean change / to - ) but it doesn't have change too!
whats the problem?
You should really be running a query like this if your problemTime column is datetime type:
SELECT * FROM aa
WHERE
problemTime>= str_to_date('2016/03/20', '%Y/%m/%d') AND
problemTime <= str_to_date('2016/04/20', '%Y/%m/%d')
Don't rely on implicit conversions between string and date.. leave your table data alone and ensure you explicitly convert your where clause parameters to the same data type as in the table. Also remember that a date "without" a time is actually midnight on the day in question, and midnight is like zero, it's the first thing that happens on any given day. A time of 6am on a given date, is after midnight, so a query that asks for dates less than or equal to midnight on a particular date means the 6am date will be excluded
This is general good DB practice; do not convert table data where possible, because it can cause huge performance hits and wrong results
Your column "problemTime" have date with time. Do not convert table data, change your where clause (add time).
SELECT * FROM aa WHERE problemTime>= '2016/03/20 00:00:00' AND problemTime<= '2016/04/20 23:59:59'
Try this as per SQl Server.
SELECT * FROM aa
WHERe cast(problemTime AS date) between '2016/03/21' AND '2016/04/20'
I have to perform a query on a MySQL database.
I have a table with records, have a column called "date" (the date type), and a column called "time" (type. Integer is stored by multiplying the time of day by 60. eg 8 am is stored as 480).
Unfortunately, the format of this table can not be modified.
My table stores attentions of doctors on call. The doctors on duty working in two shifts: from 8-20, and 20-8.
I need to know the amount of attention for every doctor.
My query must be filtered by date range and shift.
The problem is that, in the case of doctors working at the turn of 20-8, I have to consider a change of day. (sorry for my bad English).
What I have done is this, this would be an example to date of yesterday, and doctors shift 20-8.
SELECT * FROM attentions WHERE (date >= '2015-07-23' and time >=1200) and (date <= '2015-07-24' and time <480)
the query does not work at all.
Supposing the date field is called: 'a_date' with format 'yyyy-mm-ss' and the time field is a number, the query should be:
SELECT * FROM attentions WHERE (date(a_date) >= '2015-07-23' and time >=1200) and (date(a_date) <= '2015-07-24' and time <480)
Can you check using between?
SELECT * FROM attentions WHERE date between '2015-07-23' and '2015-07-24' and time between 1200 and 480
I think you can also use this -
SELECT * FROM ***** where CREATED_DATETIME between '2015-03-12 00:00:00' and '2015-05-11 00:00:00';
I need to create a query to select some data of my mysql db based on date, but in my where clause i have to options:
1 - trunc the date:
select count(*) from mailing_user where date_format(create_date, '%Y-%m-%d')='2013-11-05';
2 - use between
select count(*) from mailing_user where create_date between '2013-11-05 00:00:00' and '2013-11-05 23:59:59';
the two query's will work, but whats the better? Or, what's recommended? Why?
Here is an article to read.
http://willem.stuursma.name/2009/01/09/mysql-performance-with-date-functions/
If your created_date column is indexed, the 2nd query will be faster.
But if the column is not indexed and if this is your defined date format, you can use the following query.
select count(*) from mailing_user where DATE(create_date) = '2013-11-05';
I use DATE instead of DATE_FORMAT as I can make use of the native feature of getting in this format('2013-11-05').
From your question it seems you want to select records from one day, according to the documentation A DATETIME or TIMESTAMP value can include a trailing fractional seconds part in up to microseconds (6 digits) precision.
So this means your second query might actually get unlucky and miss some records that were inserted into the table at the very last second of that day, so that is why I would say the first one is more precise and is guaranteed to always get you the correct result.
The downside of this is that you cannot index that column using the date_format-function, because MySQL isn't cool with that.
If you don't want to use date_format and get around the precision issue you would change
where create_date between '2013-11-05 00:00:00' and '2013-11-05 23:59:59'
into
where create_date >= '2013-11-05 00:00:00' and create_date < '2013-12-05 00:00:00'
Number 2 will be faster if you have an index on the create_date because number one won't be able to use the index to quickly scan the results.
However this requires there to be an index on the create_date.
Otherwise I imagine they would be similar speed, possibly the second would still be faster because of the smaller processing time to compare(datetime comparison rather than converting to a string and comparing strings), but I doubt it'd be significant.
http://upic.me/i/hq/capture.png
http://upic.me/i/3g/capture.png
I have the table that divide datetime to single field and set these field to index.
i would to use where clause in date range ex. between 2010/06/21 to 2011/05/15
I try to use
where concat_ws('-',year,month,day) between '2010/06/21' and '2011/05/15'
it's work because I use concat function to adjust these field like ordinary datetime
but it not use index and query slowly.This table has 3 million record
if would to use index I try to this query
where
year = '2011'
and month between 05 and 06
and day between 21 and 15
It almost work but in last line
day between 21 and 15
I can't use this condition
I try to solve this problem but I can't find it and change structer table
I'm looking for answer
thank you
Now I can OR operation for query thank for your answer
In another case if would to find 2009/08/20 to 2011/04/15 It's use longer query and make confusion.Has someone got idea?
If it's a datestamp type, you can just use the where/between clause directly. I would consider switching to that, it's quite faster than a varchar with a custom date format.
WHERE yourdate BETWEEN "2011-05-01" AND "2011-06-15"
Although checking ranges may work for single months, you will find if you're querying between several months to have some margin of error because, if you think about it, you're selecting more than you may necessarily want. Using Datestamp will fix performance and usability issues arising from storing the date in a custom varchar.
Here are the two queries to convert your times around if you're interested:
ALTER TABLE `yourtable` ADD `newdate` DATE NOT NULL;
UPDATE `yourtable` SET `newdate` = STR_TO_DATE(`olddate`, '%Y/%m/%d');
Just change "yourtable", "newdate", and "olddate" to your table's name, the new date column name, and the old datestamp column names respectively.
If you can't change the table structure, you could use something like the following:
WHERE year = '2011'
AND ((month = '05' AND day >= 21) OR (month = '06' AND day <= '15'))
(At least, I think that query does what you want in your specific case. But for e.g. a longer span of time, you'd have to think about the query again, and I suspect queries like this could become a pain to maintain)
UPDATE for the updated requirement
The principle remains the same, only the query becomes more complex. For the range of 2009/08/20 to 2011/04/15 it might look like this:
WHERE year = '2009' AND (month = '08' AND day >= '20' OR month BETWEEN '09' AND '12')
OR year = '2010'
OR year = '2011' AND (month BETWEEN '01' AND '03' OR month = '04' AND day <= '15')
where year = 2011
and (month between 5 and 6) and (day > 20 or day < 16)
You where seperating days and month whereas you must keep them together
parentheses must be set ...
Mike
It is important that you use OR otherwise it is nonsense