HI
I have a table listsing_prices (id,listing_id,day_from,day_to,price)
I need to calculate the total cost of an holiday in mysql becouse I need to sort the results by total cost.
EX:
VALUES IN TABLE
1 6 2011-04-27 2011-04-30 55,00
2 6 2011-05-01 2011-05-02 60,00
3 6 2011-05-03 2011-05-15 65,00
holiday from 2011-04-28 to 2011-05-05 total cost = 480
Without creating an actual table to represent every day from start date to end date, you could use mysql query variables. The first query can join to any table as long as it has as many records as days you are concerned with for the hoiday period... in this case, 8 days from April 28 to May 5. By doing a Cartesian and limiting to 8 will in essence, create a temp result set with one record per each day, starting with 2011/04/28 (your starting date).
Then, this is joined back to your pricing table that matches the date period and sums the matching price for total costs...
select
sum( pt.price ) as TotalCosts
from
( SELECT
#r:= date_add(#r, interval 1 day ) CalendarDate
FROM
(select #r := STR_TO_DATE('2011/04/28', '%Y/%m/%d')) vars,
AnyTableWithAtLeast8ays limit 8 ) JustDates,
PricesTable pt
where
JustDates.CalendarDate between pt.date_from and pt.date_to
select count(price) from listing_prices where day_from >= '2011-04-28' and day_to <= '2011-05-05'
-- This will provide a list of ids along with how many days fall between the two
SELECT a.id, DATEDIFF(DAYS, CASE WHEN day_from < '2011-04-28' THEN '2011-04-28' ELSE day_from END CASE, day_to) AS DayCount
FROM listing_prices a
WHERE '2011-04-28' BETWEEN a.date_from AND a.date_to
AND a.date_to <= '2011-05-05'
-- Based on the previous query, sum the number of days within the range
SELECT SUM( a.price * b.DayCount ) AS Total
FROM listing_prices a
JOIN ( SELECT a.id, DATEDIFF(DAYS, CASE WHEN day_from < '2011-04-28' THEN '2011-04-28' ELSE day_from END CASE, day_to) AS DayCount
FROM listing_prices a
WHERE '2011-04-28' BETWEEN a.date_from AND a.date_to
AND a.date_to <= '2011-05-05'
) b ON a.id = b.id
Please note that this is untested ... the query at the top I believe should work but if it doesn't, it can be modified and so that it does work (get the number of days within each range) and then literally copied and pasted into the subquery of the second query. The second query is the one that you will actually use.
Related
I'm trying to fetch the records with half an hour time interval of the current day with concern data count for that time period.
So, my output came as expected. But, If count(no records) on the particular time period let's say 7:00 - 7:30 I'm not getting that record with zero count.
My Query as follows :
SELECT time_format( FROM_UNIXTIME(ROUND(UNIX_TIMESTAMP(start_time)/(30* 60)) * (30*60)) , '%H:%i')
thirtyHourInterval , COUNT(bot_id) AS Count FROM bot_activity
WHERE start_time BETWEEN CONCAT(CURDATE(), ' 00:00:00') AND CONCAT(CURDATE(), ' 23:59:59')
GROUP BY ROUND(UNIX_TIMESTAMP(start_time)/(30* 60))
For reference of my output :
We need a source for that 7:30 row; a row source for all the time values.
If we have a clock table that contains all of the time values we want to return, such that we can write a query that returns that first column, the thirty minute interval values we want to return,
as an example:
SELECT c.hhmm AS thirty_minute_interval
FROM clock c
WHERE c.hhmm ...
ORDER BY c.hhmm
then we can do an outer join the results of the query with the missing rows
SELECT c.hhmm AS _thirty_minute_interval
, IFNULL(r._cnt_bot,0) AS _cnt_bot
FROM clock c
LEFT
JOIN ( -- query with missing rows
SELECT time_format(...) AS thirtyMinuteInterval
, COUNT(...) AS _cnt_bot
FROM bot_activity
WHERE
GROUP BY time_format(...)
) r
ON r.thirtyMinuteInterval = c.hhmm
WHERE c.hhmm ...
ORDER BY c.hhmm
The point is that the SELECT will not generate "missing" rows from a source where they don't exist; we need a source for them. We don't necessarily have to have a separate clock table, we could have an inline view generate the rows. But we do need to be able to SELECT those value from a source.
( Note that bot_id in the original query is indeterminate; the value will be from some row in the collapsed set of rows, but no guarantee which value. (If we add ONLY_FULL_GROUP_BY to sql_mode, the query will throw an error, like most other relational databases will when non-aggregate expressions in the SELECT list don't appear in the GROUP BY are aren't functionally dependent on the GROUP BY )
EDIT
In place of a clock table, we can use an inline view. For small sets, we could something like this.
SELECT c.tmi
FROM ( -- thirty minute interval
SELECT CONVERT(0,TIME) + INTERVAL h.h+r.h HOUR + INTERVAL m.mm MINUTE AS tmi
FROM ( SELECT 0 AS h UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3
UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7
UNION ALL SELECT 8 UNION ALL SELECT 9 UNION ALL SELECT 10 UNION ALL SELECT 11
) h
CROSS JOIN ( SELECT 0 AS h UNION ALL SELECT 12 ) r
CROSS JOIN ( SELECT 0 AS mm UNION ALL SELECT 30 ) m
ORDER BY tmi
) c
ORDER
BY c.tmi
(Inline view c is a standin for a clock table, returns time values on thirty minute boundaries.)
That's kind of ugly. We can see where if we had a rowsource of just integer values, we could make this much simpler. But if we pick that apart, we can see how to extend the same pattern to generate fifteen minute intervals, or shorten it to generate two hour intervals.
Given a database table that contains a list of race times, I need to be able to identify which of the performances are faster than earlier finish times for that athlete at a specific distance, e.g. it was their best time at the time of the performance.
Also, would it be better to update this and store as a boolean in an additional column at rest, rather than trying to calculate when doing a SELECT. The database isn't populated in chronological order, so not sure if a TRIGGER would help. I was thinking of a query that runs on the whole table after any inserts/updates. Appreciate this may have a performance impact, so could be run periodically rather than on each row update.
This is on a MySQL 5.6.47 server.
Example table
athleteId date distance finishTime
1 2020-01-04 5K 30:00
1 2020-01-11 5K 30:09
1 2020-01-18 5K 29:45
1 2020-01-25 5K 29:32
1 2020-02-01 5K 31:18
1 2020-02-02 10K 1:06:07
1 2020-02-08 5K 28:25
1 2020-02-23 10K 1:06:02
1 2020-02-23 10K 1:07:30
Expected output
athleteId date distance finishTime isPersonalBest
1 2020-01-04 5K 30:00 Y
1 2020-01-11 5K 30:09 N
1 2020-01-18 5K 29:45 Y
1 2020-01-25 5K 29:32 Y
1 2020-02-01 5K 31:18 N
1 2020-02-02 10K 1:06:07 Y
1 2020-02-08 5K 28:25 Y
1 2020-02-23 10K 1:06:02 Y
1 2020-02-23 10K 1:07:30 N
The data is just an example. The actual finish times are stored in seconds. There will be many more athletes and different event distances. If a performance is the first for that athlete at that distance, it would be classed as a personal best.
If you are running MysQL 8.0, you can use window functions:
select
t.*,
case when finishTime < min(finishTime) over(
partition by athleteId, distance
order by date
rows between unbounded preceding and 1 preceding
)
then 'Y'
else 'N'
end isPersonalBest
from mytable t
In earlier versions, one option is a correlated subquery:
select
t.*,
case when exists(
select 1
from mytable t1
where
t1.athleteId = t.athleteId
and t1.distance = t.distance
and t1.date < t.date
and t1.finishTime <= t.finishTime
)
then 'N'
else 'Y'
end isPersonalBest
from mytable t
I wouldn't recommend actually storing this derived information. Instead, you use the above query to create a view.
You can use a cumulative min in MySQL 8+:
select t.*,
(case when finishTime >=
min(finishTime) over (partition by athleteid, distance
order by date
rows between unbounded preceding and 1 preceding
)
then 'N' else 'Y'
end) as isPersonalBest
from t;
Here is a db<>fiddle.
In earlier versions, you could use not exists:
select t.*,
(case when not exists (select 1
from t t2
where t2.atheleteid = t.athleteid and
t2.distance = t.distance and
t2.date < t.date and
t2.finishTime <= t.finishTime
)
then 'Y' else 'N'
end) as isPersonalBest
from t;
I have the following table denoting a tutor teaching pupils in small groups. Each pupil has an entry into the database. A pupil may be alone or in a group. I wish to calculate the tutors "salary" as such: payment is based on time spent - this means that for each sitting (with one or more pupils) only one sitting will be calculated - distinct sittings! The start and end times are unix times.
<pre>
start end attendance
1359882000 1359882090 1
1359867600 1359867690 0
1359867600 1359867690 1
1359867600 1359867690 0
1360472400 1360477800 1
1360472400 1360477800 1
1359867600 1359867690 1
1359914400 1359919800 1
1360000800 1360006200 1
1360000800 1360006200 0
1360000800 1360006200 1
</pre>
This is what I tried: with no success - I can't get the right duration (number of hours for all distinct sittings)
SELECT YEAR(FROM_UNIXTIME(start)) AS year,
MONTHNAME(STR_TO_DATE(MONTH(FROM_UNIXTIME(start)), '%m')) AS month,
COUNT(DISTINCT start) AS sittings,
SUM(TRUNCATE((end-start)/3600, 1)) as duration
FROM schedules
GROUP BY
YEAR(FROM_UNIXTIME(start)),
MONTH(FROM_UNIXTIME(start))
Thanks for your proposals / support!
EDIT: Required results
Rate = 25
Year Month Sittings Duration Bounty
2013 February 2 2.2 2.2*25
2013 April 4 12.0 12.0*25
You could probably do something with subqueries, I've had a play with SQL fiddle, how does this look for you. Link to sql fiddle : http://sqlfiddle.com/#!2/50718c/3
SELECT
YEAR(d.date) AS year,
MONTH(d.date) AS month,
COUNT(*) AS sittings,
SUM(d.duration) AS duration_mins
FROM (
SELECT
DATE(FROM_UNIXTIME(s.start)) AS date,
s.attendance,
end-start AS duration
FROM schedules s
) d
GROUP BY
year,
month
I couldn't really see where attendance comes into this at present, you didn't specify. The inner query is responsible for taking the schedules, extracting a start date, and a duration (in seconds).
The outer query then uses these derived values but groups them up to get the sums. You could elaborate from here i.e. maybe you only want to select where attendance > 0, or maybe you want to multiply by attendance.
In this next example I have done this, calculating the duration in hours instead, and calculating the applicable duration for where sessions have >1 attendance along with the appropriate bounty assuming bounty == hours * rate : http://sqlfiddle.com/#!2/50718c/21
SELECT
YEAR(d.date) AS year,
MONTH(d.date) AS month,
COUNT(*) AS sittings,
SUM(d.duration) AS duration,
SUM(
IF(d.attendance>0,1,0)
) AS sittingsWorthBounty,
SUM(
IF(d.attendance>0,d.duration,0)
) AS durationForBounty,
SUM(
IF(d.attendance>0,d.bounty,0)
) AS bounty
FROM (
SELECT
DATE(FROM_UNIXTIME(s.start)) AS date,
s.attendance,
(end-start)/3600 AS duration,
(end-start)/3600 * #rate AS bounty
FROM schedules s,
(SELECT #rate := 25) v
) d
GROUP BY
year,
month
The key point here, is that in the subquery you do all the calculation per-row. The main query then is responsible for grouping up the results and getting your totals. The IF statements in the outer query could easily be moved into the subquery instead, for example. I just included them like this so you could see where the values came from.
I have a simple MySQL table like below, used to compute MPG for a car.
+-------------+-------+---------+
| DATE | MILES | GALLONS |
+-------------+-------+---------+
| JAN 25 1993 | 20.0 | 3.00 |
| FEB 07 1993 | 55.2 | 7.22 |
| MAR 11 1993 | 44.1 | 6.28 |
+-------------+-------+---------+
I can easily compute the Miles Per Gallon (MPG) for the car using a select statement, but because the MPG varies widely from fillup to fillup (i.e. you don't fill the exact same amount of gas each time), I would like to computer a 'MOVING AVERAGE' as well. So for any row the MPG is MILES/GALLON for that row, and the MOVINGMPG is the SUM(MILES)/SUM(GALLONS) for the last N rows. If less than N rows exist by that point, just SUM(MILES)/SUM(GALLONS) up to that point.
Is there a single SELECT statement that will fetch the rows with MPG and MOVINGMPG by substituting N into the select statement?
Yes, it's possible to return the specified resultset with a single SQL statement.
Unfortunately, MySQL does not support analytic functions, which would make for a fairly simple statement. Even though MySQL does not have syntax to support them, it is possible to emulate some analytic functions using MySQL user variables.
One of the ways to achieve the specified result set (with a single SQL statement) is to use a JOIN operation, using a unique ascending integer value (rownum, derived by and assigned within the query) to each row.
For example:
SELECT q.rownum AS rownum
, q.date AS latest_date
, q.miles/q.gallons AS latest_mpg
, COUNT(1) AS cnt_rows
, MIN(r.date) AS earliest_date
, SUM(r.miles) AS rtot_miles
, SUM(r.gallons) AS rtot_gallons
, SUM(r.miles)/SUM(r.gallons) AS rtot_mpg
FROM ( SELECT #s_rownum := #s_rownum + 1 AS rownum
, s.date
, s.miles
, s.gallons
FROM mytable s
JOIN (SELECT #s_rownum := 0) c
ORDER BY s.date
) q
JOIN ( SELECT #t_rownum := #t_rownum + 1 AS rownum
, t.date
, t.miles
, t.gallons
FROM mytable t
JOIN (SELECT #t_rownum := 0) d
ORDER BY t.date
) r
ON r.rownum <= q.rownum
AND r.rownum > q.rownum - 2
GROUP BY q.rownum
Your desired value of "n" to specify how many rows to include in each rollup row is specified in the predicate just before the GROUP BY clause. In this example, up to "2" rows in each running total row.
If you specify a value of 1, you will get (basically) the original table returned.
To eliminate any "incomplete" running total rows (consisting of fewer than "n" rows), that value of "n" would need to be specified again, adding:
HAVING COUNT(1) >= 2
sqlfiddle demo: http://sqlfiddle.com/#!2/52420/2
Followup:
Q: I'm trying to understand your SQL statement. Does your solution do a select of twenty rows for each row in the db? In other words, if I have 1000 rows will your statement perform 20000 selects? (I'm worried about performance)...
A: You are right to be concerned with performance.
To answer your question, no, this does not perform 20,000 selects for 1,000 rows.
The performance hit comes from the two (essentially identical) inline views (aliased as q and r). What MySQL does with these (basically) is create temporary MyISAM tables (MySQL calls them "derived tables"), which are basically copies of mytable, with an extra column, each row assigned a unique integer value from 1 to the number of rows.
Once the two "derived" tables are created and populated, MySQL runs the outer query, using those two "derived" tables as a row source. Each row from q, is matched with up to n rows from r, to calculate the "running total" miles and gallons.
For better performance, you could use a column already in the table, rather than having the query assign unique integer values. For example, if the date column is unique, then you could calculate "running total" over a certain period of days.
SELECT q.date AS latest_date
, SUM(q.miles)/SUM(q.gallons) AS latest_mpg
, COUNT(1) AS cnt_rows
, MIN(r.date) AS earliest_date
, SUM(r.miles) AS rtot_miles
, SUM(r.gallons) AS rtot_gallons
, SUM(r.miles)/SUM(r.gallons) AS rtot_mpg
FROM mytable q
JOIN mytable r
ON r.date <= q.date
AND r.date > q.date + INTERVAL -30 DAY
GROUP BY q.date
(For performance, you would want an appropriate index defined with date as a leading column in the index.)
For the first query, any predicates included (in the inline view definition queries) to reduce the number of rows returned (for example, return only date values in the past year) would reduce the number of rows to be processed, and would also likely improve performance.
Again, to your question about running 20,000 selects for 1,000 rows... a nested loops operation is another way to get the same result set. For a large number of rows, this can exhibit slower performance. (On the other hand, this approach can be fairly efficient, when only a few rows are being returned:
SELECT q.date AS latest_date
, q.miles/q.gallons AS latest_mpg
, ( SELECT SUM(r.miles)/SUM(r.gallons)
FROM mytable r
WHERE r.date <= q.date
AND r.date >= q.date + INTERVAL -90 DAY
) AS rtot_mpg
FROM mytable q
ORDER BY q.date
Something like this should work:
SELECT Date, Miles, Gallons, Miles/Gallons as MilesPerGallon,
#Miles:=#Miles+Miles overallMiles,
#Gallons:=#Gallons+Gallons overallGallons,
#RunningTotal:=#Miles/#Gallons runningTotal
FROM YourTable
JOIN (SELECT #Miles:= 0) t
JOIN (SELECT #Gallons:= 0) s
SQL Fiddle Demo
Which produces the following:
DATE MILES GALLONS MILESPERGALLON RUNNINGTOTAL
January, 25 1993 20 3 6.666667 6.666666666667
February, 07 1993 55.2 7.22 7.645429 7.358121330724
March, 11 1993 44.1 6.28 7.022293 7.230303030303
--EDIT--
In response to the comment, you can add another Row Number to limit your results to the last N rows:
SELECT *
FROM (
SELECT Date, Miles, Gallons, Miles/Gallons as MilesPerGallon,
#Miles:=#Miles+Miles overallmiles,
#Gallons:=#Gallons+Gallons overallGallons,
#RunningTotal:=#Miles/#Gallons runningTotal,
#RowNumber:=#RowNumber+1 rowNumber
FROM (SELECT * FROM YourTable ORDER BY Date DESC) u
JOIN (SELECT #Miles:= 0) t
JOIN (SELECT #Gallons:= 0) s
JOIN (SELECT #RowNumber:= 0) r
) t
WHERE rowNumber <= 3
Just change your ORDER BY clause accordingly. And here is the updated fiddle.
Data:
values date
14 1.1.2010
20 1.1.2010
10 2.1.2010
7 4.1.2010
...
sample query about january 2010 should get 31 rows. One for every day. And values vould be added. Right now I could do this with 31 queries but I would like this to work with one. Is it possible?
results:
1. 34
2. 10
3. 0
4. 7
...
This is actually surprisingly difficult to do in SQL. One way to do it is to have a long select statement with UNION ALLs to generate the numbers from 1 to 31. This demonstrates the principle but I stopped at 4 for clarity:
SELECT MonthDate.Date, COALESCE(SUM(`values`), 0) AS Total
FROM (
SELECT 1 AS Date UNION ALL
SELECT 2 UNION ALL
SELECT 3 UNION ALL
SELECT 4 UNION ALL
--
SELECT 28 UNION ALL
SELECT 29 UNION ALL
SELECT 30 UNION ALL
SELECT 31) AS MonthDate
LEFT JOIN Table1 AS T1
ON MonthDate.Date = DAY(T1.Date)
AND MONTH(T1.Date) = 1 AND YEAR(T1.Date) = 2010
WHERE MonthDate.Date <= DAY(LAST_DAY('2010-01-01'))
GROUP BY MonthDate.Date
It might be better to use a table to store these values and join with it instead.
Result:
1, 34
2, 10
3, 0
4, 7
Given that for some dates you have no data, you'll need to fill in the gaps. One approach to this is to have a calendar table prefilled with all dates you need, and join against that.
If you want the results to show day numbers as you have showing in your question, you could prepopulate these in your calendar too as labels.
You would join your data table date field to the date field of the calendar table, group by that field, and sum values. You might want to specify limits for the range of dates covered.
So you might have:
CREATE TABLE Calendar (
label varchar,
cal_date date,
primary key ( cal_date )
)
Query:
SELECT
c.label,
SUM( d.values )
FROM
Calendar c
JOIN
Data_table d
ON d.date_field = c.cal_date
WHERE
c.cal_date BETWEEN '2010-01-01' AND '2010-01-31'
GROUP BY
d.date_field
ORDER BY
d.date_field
Update:
I see you have datetimes rather than dates. You could just use the MySQL DATE() function in the join, but that would probably not be optimal. Another approach would be to have start and end times in the Calendar table defining a 'time bucket' for each day.
This works for me... Its a modification of a query I found on another site. The "INTERVAL 1 MONTH" clause ensures I get the current month data, including zeros for days that have no hits. Change this to "INTERVAL 2 MONTH" to get last months data, etc.
I have a table called "payload" with a column "timestamp" - Im then joining the timestamp column on to the dynamically generated dates, casting it so that the dates match in the ON clause.
SELECT `calendarday`,COUNT(P.`timestamp`) AS `cnt` FROM
(SELECT #tmpdate := DATE_ADD(#tmpdate, INTERVAL 1 DAY) `calendarday`
FROM (SELECT #tmpdate :=
LAST_DAY(DATE_SUB(CURDATE(),INTERVAL 1 MONTH)))
AS `dynamic`, `payload`) AS `calendar`
LEFT JOIN `payload` P ON DATE(P.`timestamp`) = `calendarday`
GROUP BY `calendarday`
To dynamically get the dates within a date range using SQL you can do this (example in mysql):
Create a table to hold the numbers 0 through 9.
CREATE TABLE ints ( i tinyint(4) );
insert into ints (i)
values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
Run a query like so:
select ((curdate() - interval 2 year) + interval (t.i * 100 + u.i * 10 + v.i) day) AS Date
from
ints t
join ints u
join ints v
having Date between '2015-01-01' and '2015-05-01'
order by t.i, u.i, v.i
This will generate all dates between Jan 1, 2015 and May 1, 2015.
Output
2015-01-01
2015-01-02
2015-01-03
2015-01-04
2015-01-05
2015-01-06
...
2015-05-01
The query joins the table ints 3 times and gets an incrementing number (0 through 999). It then adds this number as a day interval starting from a certain date, in this case a date 2 years ago. Any date range from 2 years ago and 1,000 days ahead can be obtained with the example above.
To generate a query that generates dates for more than 1,000 days simply join the ints table once more to allow for up to 10,000 days of range, and so forth.
If I'm understanding the rather vague question correctly, you want to know the number of records for each date within a month. If that's true, here's how you can do it:
SELECT COUNT(value_column) FROM table WHERE date_column LIKE '2010-01-%' GROUP BY date_column