I have a MySQL DB where one column is the DATE and the other column is the SIGNAL. Now I would like to calculate the SUM over Signal for 4 days each.
f.e.
SUM(signal over DATE1,DATE2,DATE3,DATE4)
SUM(signal over DATE5,DATE6,DATE7,DATE8)
...
whereas Date_N = successor of DATE_N-1 but need not to be the day before
Moreless the algo should be variable in the days group. 4 ist just an example.
Can anyone here give me an advice how to perform this in MySQL?
I have found this here group by with count, maybe this could be helpful for my issue?
Thanks
Edit: One important note: My date ranges have gaps in it. you see this in the picture below, in the column count(DISTINCT(TradeDate)). It should be always 4 when I have no gaps. But I DO have gaps. But when I sort the date descending, I would like to group the dates together always 4 days, f.e. Group1: 2017-08-22 + 2017-08-21 + 2017-08-20 + 2017-08-19, Group2: 2017-08-18 + 2017-08-17+2017-08-15+2017-08-14, ...
maybe I could map the decending dateranges into a decending integer autoincrement number, then I would have a number without gaps. number1="2017-08-17" number2="2017-08-15" and so on ..
Edit2:
As I see the result from my table with this Query: I might I have double entries for one and the same date. How Can I distinct this date-doubles into only one reprensentative?
SELECT SUM(CondN1),count(id),count(DISTINCT(TradeDate)),min(TradeDate),max(TradeDate) ,min(TO_DAYS(DATE(TradeDate))),id FROM marketstat where Stockplace like '%' GROUP BY TO_DAYS(DATE(TradeDate)) DIV 4 order by TO_DAYS(DATE(TradeDate))
SUM() is a grouping function, so you need to GROUP BY something. That something should change only every four days. Let's start by grouping by one day:
SELECT SUM(signal)
FROM tableName
GROUP BY date
date should really be of type DATE, like you mentioned, not DATETIME or anything else. You could use DATE(date) to convert other date types to dates. Now we need to group by four dates:
SELECT SUM(signal)
FROM tableName
GROUP BY TO_DAYS(date) DIV 4
Note that this will create an arbitary group of four days, if you want control over that you can add a term like this:
SELECT SUM(signal)
FROM tableName
GROUP BY (TO_DAYS(date)+2) DIV 4
In the meantime and with help of KIKO I have found the solution:
I make a temp table with
CREATE TEMPORARY TABLE if not EXISTS tradedatemaptmp (id INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY) SELECT Tradedate AS Tradedate, CondN1, CondN2 FROM marketstat WHERE marketstat.Stockplace like 'US' GROUP BY TradeDate ORDER BY TradeDate asc;
and use instead the originate tradedate the now created id in the temp table. So I could manage that - even when I have gaps in the tradedate range, the id in the tmp table has no gaps. And with this I can DIV 4 and get the always the corresponding 4 dates together.
Related
please, I want to select from mysql tables where the absolute difference between two columns is the smallest value between the absolute difference values.
I tried this syntax but it was not right
SELECT strike FROM options_20161230 ORDER BY ask - bid ASC LIMIT 1
I wonder if I can create a new column in the table as the difference between two columns, is that possible?
also I want to select where one column has a value between two numbers, I tried this
SELECT strike FROM options_20161230 WHERE 7 < Expiration - Datadate < 37 AND type ='put' AND UnderlyingSymbol = 'SPY'
it works when limited Expiration - Datadate by one value < 37. however It was not working with two values <,> ?
any idea please!
Many Thanks
Your first query is close. You just want abs():
SELECT strike
FROM options_20161230
ORDER BY abs(ask - bid) ASC
LIMIT 1;
Your third query should use between (assuming the difference is an integer) or two inequalities:
SELECT strike
FROM options_20161230
WHERE Expiration - Datadate BETWEEN 8 AND 36 AND
type ='put' AND
UnderlyingSymbol = 'SPY';
I have attendance data for employees stored in the table attendance with the following column names:
emp_id (employee ID)
date
type (leave, absent, etc.)
(there are others but I'm omitting them for the sake of simplicity)
My objective is to retrieve all dates of the given month on which the employee was on leave (type = 'Leave') and the last leave taken in the last month, if any.
It's easy to do it using two queries (I'm using PHP to get process the data), but is there any way this can be done in a single query?
I'm answering my own question so as to close it. As #bpgergo pointed out in the comments, UNION will do the trick here.
SELECT * FROM table_name
WHERE type="Leave" AND
date <= (CURRENT_DATE() - 30)
Select the fields, etc you want then se a combined where clause using mysql's CURRENT_DATE() function. I subtracted 30 for 30 days in a month.
If date is a date column, this will return everyone who left 1 month or longer ago.
Edit:
If you want a specific date, change the 2nd month like this:
date <= (date_number - 30)
I have a query that shows me the number of calls per day for the last 14 days within my app.
The query:
SELECT count(id) as count, DATE(FROM_UNIXTIME(timestamp)) as date FROM calls GROUP BY DATE(FROM_UNIXTIME(timestamp)) DESC LIMIT 14
On days where there were 0 calls, this query does not show those days. Rather than skip those days, I'd like to have a 0 or NULL in that spot.
Any ideas for how I can achieve this? If you have any questions as to what I'm asking please let me know.
Thanks
I don't believe your query is "skipping over NULL values", as your title suggests. Rather, your data probably looks something like this:
id | timestamp
----+------------
1 | 2014-01-01
2 | 2014-01-02
3 | 2014-01-04
As a result, there are no rows that contain the missing date, so there are no rows to be counted. The answer is that you need to generate a list of all the dates you want and then do a LEFT or RIGHT JOIN to it.
Unfortunately, MySQL doesn't make this as easy as other databases. There doesn't seem to be an effective way of generating a list of anything inline. So you'll need some sort of table.
I think I would create a static table containing a set of integers to be subtracted from the current date. Then you can use this table to generate your list of dates inline and JOIN to it.
CREATE TABLE days_ago_list (days_ago INTEGER);
INSERT INTO days_ago_list VALUES
(0),(1),(2),(3),(4),(5),(6),(7),(8),(9),(10),(11),(12),(13)
;
Then:
SELECT COUNT(id), list_date
FROM (SELECT SUBDATE(CURDATE(), days_ago) AS list_date FROM days_ago_list) dates_to_list
LEFT JOIN (SELECT id, DATE(FROM_UNIXTIME(timestamp)) call_date FROM calls) calls_with_date
ON calls_with_date.call_date = dates_to_list.list_date
GROUP BY list_date
It is very important that you group by list_date; call_date will be NULL for any days without calls. It is also important to COUNT on id since NULL ids will not be counted. (That ensures you get a correct count of 0 for days with no calls.) If you need to change the dates listed, you simply update the table containing the integer list.
Here is a SQL Fiddle demonstrating this.
Alternatively, if this is for a web application, you could generate the list of dates code side and match up the counts with the dates after the query is done. This would make your web app logic somewhat more complicated, but it would also simplify the query and eliminate the need for the extra table.
create a table that contains a row for each date you want to ensure is in the results, left outer join with results of your current query, use temp table's date, count of above query and 0 if that count is null
I have one table which is having four fields:
trip_paramid, creation_time, fuel_content,vehicle_id
I want to find the difference between two rows.In my table i have one field fuel_content.Every two minutes i getting packets and inserting to database.From this i want to find out total refuel quantity.If fuel content between two packets is greater than 2,i will treat it as refueling quantity.Multiple refuel may happen in same day.So i want to find out total refuel quantity for a day for a vehicle.I created one table schema&sample data in sqlfiddle. Can anyone help me to find a solution for this.here is the link for table schema..http://www.sqlfiddle.com/#!2/4cf36
Here is a good query.
Parameters (vehicle_id=13) and (date='2012-11-08') are injected in the query, but they are parameters to be modified.
You can note that have I chosen an expression using creation_time<.. and creation_time>.. in instead of DATE(creation_time)='...', this is because the first expression can use indexes on "creation_time" while the second one cannot.
SELECT
SUM(fuel_content-prev_content) AS refuel_tot
, COUNT(*) AS refuel_nbr
FROM (
SELECT
p.trip_paramid
, fuel_content
, creation_time
, (
SELECT ps.fuel_content
FROM trip_parameters AS ps
WHERE (ps.vehicle_id=p.vehicle_id)
AND (ps.trip_paramid<p.trip_paramid)
ORDER BY trip_paramid DESC
LIMIT 1
) AS prev_content
FROM trip_parameters AS p
WHERE (p.vehicle_id=13)
AND (creation_time>='2012-11-08')
AND (creation_time<DATE_ADD('2012-11-08', INTERVAL 1 DAY))
ORDER BY p.trip_paramid
) AS log
WHERE (fuel_content-prev_content)>2
Test it:
select sum(t2.fuel_content-t1.fuel_content) TotalFuel,t1.vehicle_id,t1.trip_paramid as rowIdA,
t2.trip_paramid as rowIdB,
t1.creation_time as timeA,
t2.creation_time as timeB,
t2.fuel_content fuel2,
t1.fuel_content fuel1,
(t2.fuel_content-t1.fuel_content) diffFuel
from trip_parameters t1, trip_parameters t2
where t1.trip_paramid<t2.trip_paramid
and t1.vehicle_id=t2.vehicle_id
and t1.vehicle_id=13
and t2.fuel_content-t1.fuel_content>2
order by rowIdA,rowIdB
where (rowIdA,rowIdB) are all possibles tuples without repetition, diffFuel is the difference between fuel quantity and TotalFuel is the sum of all refuel quanty.
The query compare all fuel content diferences for same vehicle(in this example, for vehicle with id=13) and only sum fuel quantity when the diff fuel is >2.
Regards.
I have some data which I want to retrieve, but I want to have it grouped by a specific number of seconds. For example if my table looks like this:
| id | user | pass | created |
The created column is INT and holds a timestamp (number of seconds from 1970).
I would want the number of users that are created between last month and the current date, but show them grouped by let's say 7*24*3600 (a week). So if in the range there are 1000 new users, have them show up how many registered each week (100 the first week, 450 the second, 50 the third and 400 the 4th week -- something like this).
I've tried grouping the results by created / 7*24*3600, but that's not working.
How should my query look like?
You need to use integer division div otherwise the result will turn into a real and none of the weeks will resolve to the same value.
SELECT
(created div (7*24*60*60)) as weeknumber
, count(*) as NewUserCount
FROM users
WHERE weeknumber > 1
GROUP BY weeknumber
See: http://dev.mysql.com/doc/refman/5.0/en/arithmetic-functions.html
You've got to keep the integer part only of that division. You can do it with the floor() function.
Have you tried select floor(created/604800) as week_no, count(*) from users group by floor(created/604800) ?
I assume you've got the "select users created in the last month" part sorted out.
Okay here are the possible options you may try:
GROUP BY DAY
select count(*), DATE_FORMAT(created_at,"%Y-%m-%d") as created_day FROM widgets GROUP BY created_day
GROUP BY MONTH
select count(*), DATE_FORMAT(created_at,"%Y-%m") as created_month FROM widgets GROUP BY created_month
GROUP BY YEAR
select count(*), DATE_FORMAT(created_at,"%Y") as created_year FROM widgets GROUP BY created_year