I have a table in which rows have dates as monday dates of the weeks. Some consecutive rows may not have consecutive weekdate and thus has gaps in between. This image will clear the situation:
As clear from the image, there is a gap between weekdates 2016-08-08 and 2016-09-05 as rows with weekdates '2016-08-15','2016-08-22','2016-08-29' are not there before '2016-09-05'.
So, how can I fill this gap with rows for all these dates and null for rest two columns?
Use a tally table
either from a physically stored numbers table, see code here
or create one on-the-fly with a CTE.
You might try this code, which will generate a list of Mondays
DECLARE #start INT=0;
DECLARE #end INT=20;
DECLARE #step INT=7;
WITH x AS(SELECT 1 AS N FROM(VALUES(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) AS tbl(N))--10^1
,N3 AS (SELECT 1 AS N FROM x CROSS JOIN x AS N2 CROSS JOIN x N3) --10^3
,Tally AS(SELECT TOP(#end-#start +1) (ROW_NUMBER() OVER(ORDER BY(SELECT NULL)) + #start -1) * #step AS Nr FROM N3
CROSS JOIN N3 N6 CROSS JOIN N3 AS N9)
SELECT DATEADD(DAY,Nr,{d'2016-08-01'}) AS Monday
FROM Tally
You can specify the count of generated rows with #start and #end, the #step should be 7 in your case. This will add 0, 7, 14, 21, ... to a given date (which should be a Monday in your case).
Now use a LEFT JOIN to combine this with your table data. This should result in a gap-less list of all Mondays together with values - if there are any...
Try this:
SELECT DATEADD(week,1,[select query]) -- In select query write the query
-- to get the date to which you need to add 1 week
In the above query it will take the current date i.e 2016-09-08 15:19:06.950 and add 1 week to it and give the resultant date i.e 2016-09-15 15:19:40.657
Related
Suppose you have a room which is 100sqft and you want to rent it from 1st Aug to 31st Aug.
Bookings Table schema
startdate|enddate|area|storageid
you have following bookings
06-Aug|25-Aug|50|'abc'
05-Aug|11-Aug|40|'xyz'
18-Aug|23-Aug|30|'pqr'
13-Aug|16-Aug|10|'qwe'
Now somebody requests for booking from 08-Aug to 20-Aug. For this date range the maximum area available is 10sqft (Since, for dates 8,9,10 and 11 Aug only 10sq ft is available.)
How would you create an efficient SQL query to get this? Right now I have very messy and inefficient query which gives wrong results for some cases. I am not posting the query because It is so messy that I can't explain it myself.
I don't necessarily want to solve it using SQL only. If there is an algorithm that can solve it efficiently I would extract all the data from database.
Someone removed SQL Server, but here is the algorithm:
DECLARE #startDate date = '2016-08-09';
DECLARE #endDate date = '2016-08-20';
DECLARE #totalArea decimal(19,2) = 100;
WITH Src AS --Your source table
(
SELECT * FROM (VALUES
('2016-08-06', '2016-08-25', 50, 'abc'),
('2016-08-05', '2016-08-11', 40, 'xyz'),
('2016-08-18','2016-08-23',30,'pqr'),
('2016-08-13','2016-08-16',10,'qwe')
)T(startdate, enddate, area, storageid)
), Nums AS --Numbers table 0..N, N must be greater than ranges calculated
(
SELECT 0 N
UNION ALL
SELECT N+1 N FROM Nums
WHERE N<DATEDIFF(DAY,#startDate,#endDate)
) --Query
--You can use total-maxUsed from range of days
SELECT #totalArea-MAX(Used) FROM
(
--Group by day, sum all used areas
SELECT MidDate, SUM(Used) Used FROM
(
--Join table with numbers, split every day, if room used, return area
SELECT DATEADD(DAY, N, #startDate) MidDate, CASE WHEN DATEADD(DAY, N, #startDate) BETWEEN startDate AND endDate THEN area END Used
FROM Src
CROSS APPLY Nums
) T
GROUP BY MidDate
) T
This is a bit difficult to describe, and I'm not sure if this can be done in SQL. Using the following example data set:
ID Count Date
1 0 1/1/2015
2 3 1/5/2015
3 4 1/6/2015
4 3 1/9/2015
5 9 1/15/2015
I want to return records where the Date column falls into a range. But, if the "from" date doesn't exist in the table, I want to use the most recent date as my "From" select. For example, if my date range is between 1/5 and 1/9, I would expect to have records 2,3, and 4 returned. But, if I have a date range of 1/3 - 1/6 I want to return records 1,2,and 3. I want to include record 1 because, as 1/3 does not exist, I want the value of the Count that is rounded down.
Any thoughts on how this can be done? I'm using MySQL.
Basically, you need to replace the from date with the latest date before or on that date. Let me assume that the variables are #v_from and #v_to.
select e.*
from example e
where e.date >= (select max(e2.date) from example e2 where e2.date <= #v_from) and
e.date <= #v_to;
EDIT AFTER EDIT:
SELECT *
FROM TABLE
WHERE DATE BETWEEN (
SELECT Date
FROM TABLE
WHERE Date <= #Start
ORDER BY Date DESC
LIMIT 1
)
AND #End
Or
SELECT *
FROM TABLE
WHERE DATE BETWEEN (
SELECT MAX(Date)
FROM TABLE
WHERE Date <= #Start
)
AND #End
I've got a database of movies, and I'd like a list of years where I don't have a movie for that year. So all I need is a list (1900 .. 2012) and then I can JOIN and IN and NOT IN on that all I want.
I've got:
CREATE PROCEDURE build_years(p1 SMALLINT)
BEGIN
CREATE TEMPORARY TABLE year (year SMALLINT(5) UNSIGNED);
label1: LOOP
INSERT INTO year VALUES (p1);
SET p1 = p1 + 1;
IF p1 > 2012 THEN LEAVE label1; END IF;
END LOOP;
END
But that seems so unSQL and only marginally less kludgy then running Python code to create the same table. I'd really like something that didn't use a stored procedure, didn't use looping and didn't use an actual table, in that order of concern.
This should work until you need more than 195 years , at which point you'll need to add a UNION ALL:
SELECT Year
FROM ( SELECT #i:= #i + 1 AS YEAR
FROM INFORMATION_SCHEMA.COLLATION_CHARACTER_SET_APPLICABILITY,
( SELECT #i:= 1899) AS i
) As Y
WHERE Year BETWEEN 1900 AND 2012
ORDER BY Year;
Although I am assuming that the COLLATION_CHARACTER_SET_APPLICABILITY System table has a default size of 195 based on my trusty testing ground SQL Fiddle
I had similar problem a few years ago. My solution was:
1. Sequence table
I created a table filled with integer sequence from 0 to < as much as it will be required >:
CREATE TABLE numbers (n INT);
INSERT INTO numbers VALUES (0),(1),(2),(3),(4);
INSERT INTO numbers SELECT n+5 FROM numbers;
INSERT INTO numbers SELECT n+10 FROM numbers;
INSERT INTO numbers SELECT n+20 FROM numbers;
INSERT INTO numbers SELECT n+40 FROM numbers;
etc.
It is executed only once, so can be created from outside of your app, even by hand.
2. Select data of a needed type and range
For integers it is obvious - i.e. range 1..99:
SELECT n FROM numbers WHERE n BETWEEN 1 AND 99;
Dates - 2h intervals from now to +2 days:
SELECT date_add(now(),INTERVAL 2*n HOUR) FROM numbers WHERE n BETWEEN 0 AND 23;
So in your case it could be:
SELECT n+1900 AS n_year FROM numbers WHERE n BETWEEN 0 AND 112;
Then JOIN it on n_year.
This will return a list of 2012 to 1900 if you really want to keep it to a query..
SELECT
TO_CHAR (ADD_MONTHS (TRUNC (SYSDATE, 'YYYY'), ((rno - 1) * -12)), 'YYYY') AS "years"
FROM
(
SELECT
LEVEL rno
FROM DUAL
CONNECT BY LEVEL <=
(SELECT TO_CHAR (TRUNC (SYSDATE, 'YYYY'), 'YYYY')
- 1899
yearstobuild
FROM DUAL))
The only solution I can think of according to your wishes sucks also ...
SELECT years.year FROM
(
SELECT 1900 AS year
UNION SELECT 1901
...
UNION SELECT 2012
) AS years
LEFT OUTER JOIN yourmovietable USING (year)
WHERE yourmovietable.year IS NULL;
Using this generic query is faster:
INSERT INTO numbers SELECT n+(SELECT COUNT(*) FROM numbers) FROM numbers;
Each query execution duplicates:
INSERT INTO numbers VALUES (0),(1),(2),(3),(4);
INSERT INTO numbers SELECT n+(SELECT COUNT(*) FROM numbers) FROM numbers;
INSERT INTO numbers SELECT n+(SELECT COUNT(*) FROM numbers) FROM numbers;
INSERT INTO numbers SELECT n+(SELECT COUNT(*) FROM numbers) FROM numbers;
...
select year into temporary table blaa from (generate_series(1900,2000)) where year not in(select distinct(year) from films)
dont know if this will work but you get the drift.
I need some help with a mysql query. I've got db table that has data from Jan 1, 2011 thru April 30, 2011. There should be a record for each date. I need to find out whether any date is missing from the table.
So for example, let's say that Feb 2, 2011 has no data. How do I find that date?
I've got the dates stored in a column called reportdatetime. The dates are stored in the format: 2011-05-10 0:00:00, which is May 5, 2011 12:00:00 am.
Any suggestions?
This is a second answer, I'll post it separately.
SELECT DATE(r1.reportdate) + INTERVAL 1 DAY AS missing_date
FROM Reports r1
LEFT OUTER JOIN Reports r2 ON DATE(r1.reportdate) = DATE(r2.reportdate) - INTERVAL 1 DAY
WHERE r1.reportdate BETWEEN '2011-01-01' AND '2011-04-30' AND r2.reportdate IS NULL;
This is a self-join that reports a date such that no row exists with the date following.
This will find the first day in a gap, but if there are runs of multiple days missing it won't report all the dates in the gap.
CREATE TABLE Days (day DATE PRIMARY KEY);
Fill Days with all the days you're looking for.
mysql> INSERT INTO Days VALUES ('2011-01-01');
mysql> SET #offset := 1;
mysql> INSERT INTO Days SELECT day + INTERVAL #offset DAY FROM Days; SET #offset := #offset * 2;
Then up-arrow and repeat the INSERT as many times as needed. It doubles the number of rows each time, so you can get four month's worth of rows in seven INSERTs.
Do an exclusion join to find the dates for which there is no match in your reports table:
SELECT d.day FROM Days d
LEFT OUTER JOIN Reports r ON d.day = DATE(r.reportdatetime)
WHERE d.day BETWEEN '2011-01-01' AND '2011-04-30'
AND r.reportdatetime IS NULL;`
It could be done with a more complicated single query, but I'll show a pseudo code with temp table just for illustration:
Get all dates for which we have records:
CREATE TEMP TABLE AllUsedDates
SELECT DISTINCT reportdatetime
INTO AllUsedDates;
now add May 1st so we track 04-30
INSERT INTO AllUsedData ('2011-05-01')
If there's no "next day", we found a gap:
SELECT A.NEXT_DAY
FROM
(SELECT reportdatetime AS TODAY, DATEADD(reportdatetime, 1) AS NEXT_DAY FROM AllUsed Dates) AS A
WHERE
(A.NEXT_DATE NOT IN (SELECT reportdatetime FROM AllUsedDates)
AND
A.TODAY <> '2011-05-01') --exclude the last day
If you mean reportdatetime has the entry of "Feb 2, 2011" but other fields associated to that date are not present like below table snap
reportdate col1 col2
5/10/2011 abc xyz
2/2/2011
1/1/2011 bnv oda
then this query works fine
select reportdate from dtdiff where reportdate not in (select df1.reportdate from dtdiff df1, dtdiff df2 where df1.col1 = df2.col1)
Try this
SELECT DATE(t1.datefield) + INTERVAL 1 DAY AS missing_date FROM table t1 LEFT OUTER JOIN table t2 ON DATE(t1.datefield) = DATE(t2.datefield) - INTERVAL 1 DAY WHERE DATE(t1.datefield) BETWEEN '2020-01-01' AND '2020-01-31' AND DATE(t2.datefield) IS NULL;
If you want to get missing dates in a datetime field use this.
SELECT CAST(t1.datetime_field as DATE) + INTERVAL 1 DAY AS missing_date FROM table t1 LEFT OUTER JOIN table t2 ON CAST(t1.datetime_field as DATE) = CAST(t2.datetime_field as DATE) - INTERVAL 1 DAY WHERE CAST(t1.datetime_field as DATE) BETWEEN '2020-01-01' AND '2020-07-31' AND CAST(t2.datetime_field as DATE) IS NULL;
The solutions above seem to work, but they seem EXTREMELY slow (taking possibly hours, I waited for 30 min only) at least in my database.
This clause takes less than a second in same database (of course you need to repeat it manually dozen times and possibly change function names to find the actual dates). pvm = my datetime, WEATHER = my table.
mysql> select year(pvm) as _year,count(distinct(date(pvm))) as _days from WEATHER where year(pvm)>=2000 and month(pvm)=1 group by _year order by _year asc;
--ako
Assume this table:
id date
----------------
1 2010-12-12
2 2010-12-13
3 2010-12-18
4 2010-12-22
5 2010-12-23
How do I find the average intervals between these dates, using MySQL queries only?
For instance, the calculation on this table will be
(
( 2010-12-13 - 2010-12-12 )
+ ( 2010-12-18 - 2010-12-13 )
+ ( 2010-12-22 - 2010-12-18 )
+ ( 2010-12-23 - 2010-12-22 )
) / 4
----------------------------------
= ( 1 DAY + 5 DAY + 4 DAY + 1 DAY ) / 4
= 2.75 DAY
Intuitively, what you are asking should be equivalent to the interval between the first and last dates, divided by the number of dates minus 1.
Let me explain more thoroughly. Imagine the dates are points on a line (+ are dates present, - are dates missing, the first date is the 12th, and I changed the last date to Dec 24th for illustration purposes):
++----+---+-+
Now, what you really want to do, is evenly space your dates out between these lines, and find how long it is between each of them:
+--+--+--+--+
To do that, you simply take the number of days between the last and first days, in this case 24 - 12 = 12, and divide it by the number of intervals you have to space out, in this case 4: 12 / 4 = 3.
With a MySQL query
SELECT DATEDIFF(MAX(dt), MIN(dt)) / (COUNT(dt) - 1) FROM a;
This works on this table (with your values it returns 2.75):
CREATE TABLE IF NOT EXISTS `a` (
`dt` date NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1;
INSERT INTO `a` (`dt`) VALUES
('2010-12-12'),
('2010-12-13'),
('2010-12-18'),
('2010-12-22'),
('2010-12-24');
If the ids are uniformly incremented without gaps, join the table to itself on id+1:
SELECT d.id, d.date, n.date, datediff(d.date, n.date)
FROM dates d
JOIN dates n ON(n.id = d.id + 1)
Then GROUP BY and average as needed.
If the ids are not uniform, do an inner query to assign ordered ids first.
I guess you'll also need to add a subquery to get the total number of rows.
Alternatively
Create an aggregate function that keeps track of the previous date, and a running sum and count. You'll still need to select from a subquery to force the ordering by date (actually, I'm not sure if that's guaranteed in MySQL).
Come to think of it, this is a much better way of doing it.
And Even Simpler
Just noting that Vegard's solution is much better.
The following query returns correct result
SELECT AVG(
DATEDIFF(i.date, (SELECT MAX(date)
FROM intervals WHERE date < i.date)
)
)
FROM intervals i
but it runs a dependent subquery which might be really inefficient with no index and on a larger number of rows.
You need to do self join and get differences using DATEDIFF function and get average.