I have a table that holds a student_id and a datetime timestamp (log_time) of when they arrived at school.
I have built a query that lists the student_id alongside the time they arrived for the current week. How can I combine the results so for example from the data below student_id 4211 shows on one line with the time in tuesday, wednesday and thursday? Using GROUP BY only shows one time. I need to somehow group by the student_id but combine the day times.
SELECT
student_id,
if( (DAYOFWEEK(log_time)=2)=0, '-', DATE_FORMAT(log_time,'%H:%i:%s') ) AS monday_time,
if( (DAYOFWEEK(log_time)=3)=0, '-', DATE_FORMAT(log_time,'%H:%i:%s') ) AS tuesday_time,
if( (DAYOFWEEK(log_time)=4)=0, '-', DATE_FORMAT(log_time,'%H:%i:%s') ) AS wednesday_time,
if( (DAYOFWEEK(log_time)=5)=0, '-', DATE_FORMAT(log_time,'%H:%i:%s') ) AS thursday_time,
if( (DAYOFWEEK(log_time)=6)=0, '-', DATE_FORMAT(log_time,'%H:%i:%s') ) AS friday_time
FROM
tbl_student_register
WHERE
YEARWEEK(`log_time`, 1) = YEARWEEK(CURDATE(), 1)
This will give the following result from my data
You want a conditional aggregation:
SELECT student_id,
MAX(CASE WHEN DAYOFWEEK(log_time) = 2 THEN DATE_FORMAT(log_time, '%H:%i:%s') END) AS monday_time,
. . .
FROM tbl_student_register
WHERE YEARWEEK(`log_time`, 1) = YEARWEEK(CURDATE(), 1)
GROUP BY student_id;
The MAX() combines the values together. If there is only one entry for a given date, then it will return that entry. If there are multiple entries, you'll need to figure out the logic to handle that.
Related
I have a MySQL table running for 4 months and I have a select statement in that table, like below.
SELECT
CONCAT(
YEAR(FROM_UNIXTIME(creation_time)),
'-',
IF(
MONTH(FROM_UNIXTIME(creation_time)) < 10,
CONCAT('0', MONTH(FROM_UNIXTIME(creation_time))),
MONTH(FROM_UNIXTIME(creation_time))
)
) AS Period,
(
COUNT(CASE
WHEN system_name = 'System' THEN 1
ELSE NULL
END)
) AS "Some data",
FROM table_name
GROUP BY
Period
ORDER BY
Period DESC
Lately, I've added a new feature and a column, let's say is_rerun. This value is just added and not exist previously. Now, i would like to write a query with the current statement which checks the system_name and also the is_rerun field and if this field exists and value is 1 then return 1 and if the column not exist or it its value is zero, then return null.
I tried IF EXISTS re_run THEN 1 ELSE NULL, but no luck. I can also insert values for the previous runs but i don't want to do that. Is there any solution. Thanks.
SELECT
CONCAT(
YEAR(FROM_UNIXTIME(creation_time)),
'-',
IF(
MONTH(FROM_UNIXTIME(creation_time)) < 10,
CONCAT('0', MONTH(FROM_UNIXTIME(creation_time))),
MONTH(FROM_UNIXTIME(creation_time))
)
) AS Period,
(
COUNT(CASE
WHEN system_name = 'System' AND IF EXISTS is_rerun THEN 1
ELSE NULL
END)
) AS "Some data",
FROM table_name
GROUP BY
Period
ORDER BY
Period DESC
As a starter: you have a group by query, so you need to put is_rerun in an aggregate function.
Based on your description, I think that something like case(case when is_rerun = 1 then 1 end) should do the work: it returns 1 if any is_rerun in the group is 1, else null.
Or if you can live with 0 instead of null, then you can use a simpler expression: max(is_rerun = 1).
Note that your query could be largely simplified as for the date formating logic and the conditional count. I would phrase it as:
select
date_format(from_unixtime(creation_time),'%Y-%m') period,
sum(system_name = 'System') some_data,
max(is_rerun = 1) is_rerun
from mytable
group by period
order by period desc
Get only the biggest date:
These are check-in and check-out records of employees, some times they do twice or more entries on the system in a row. In this sample there were two check-out in a row. Assuming these rows always gonna be ordered, in the case of check-out I would like have the biggest date, and in the case of the check-in the smallest date.
In that case I would like to have this:
The smaller date was excluded:
DEMO
Try this, in this big CASE statement I increment column by one, if checkin switches from null to not null and the other way around. Then it's enough to group by this column taking max and min of checkout and checkin respectively:
select #checkinLag := null, #rn := 0;
select max(id),
functionario,
loja,
min(checkin),
max(checkout)
from (
select case when (checkinLag is null and checkin is not null) or
(checkinLag is not null and checkin is null)
then #rn := #rn + 1 else #rn end rn,
checkin,
checkout,
loja,
id,
functionario
from (
select #checkinLag checkinLag,
#checkinLag := checkin,
checkin,
checkout,
loja,
id,
functionario
from dummyTable
order by coalesce(checkin, checkout)
) a
) a group by functionario, loja, rn
I have used subqueries, to guarantee order of evaluating expressions (assigning and using of #checkinLag), as Gordon Linoff pointed.
Demo
My solution:
Select
*
from dummyTable base
where (base.checkout is null or not exists (
select
1
from dummyTable co
where co.checkout between base.checkout and DATE_ADD(base.checkout, INTERVAL 5 SECOND)
and base.id <> co.id
and base.functionario = co.functionario
and base.loja = co.loja
)) and (base.checkin is null or not exists (
select
1
from dummyTable ci
where ci.checkin between DATE_SUB(base.checkin, INTERVAL 5 SECOND) and base.checkin
and base.id <> ci.id
and base.functionario = ci.functionario
and base.loja = ci.loja
));
you can test the query here. There is no need that the rows are orderd. I choose 5 seconds as the interval where check-in/outs should be ignored.
I have a single table with rows like this: (Date, Score, Name)
The Date field has two possible dates, and it's possible that a Name value will appear under only one date (if that name was recently added or removed).
I'm looking to get a table with rows like this: (Delta, Name), where delta is the score change for each name between the earlier and later dates. In addition, only a negative change interests me, so if Delta>=0, it shouldn't appear in the output table at all.
My main challenge for me is calculating the Delta field.
As stated in the title, it should be an SQL query.
Thanks in advance for any help!
I assumed that each name can have it's own start/end dates. It can be simplified significantly if there are only two possible dates for the entire table.
I tried this out in SQL Fiddle here
SELECT (score_end - score_start) delta, name_start
FROM
( SELECT date date_start, score score_start, name name_start
FROM t t
WHERE NOT EXISTS
( SELECT 1
FROM t x
WHERE x.date < t.date
AND x.name = t.name
)
) AS start_date_t
JOIN
( SELECT date date_end, score score_end, name name_end
FROM t t
WHERE NOT EXISTS
( SELECT 1
FROM t x
WHERE x.date > t.date
AND x.name = t.name
)
) end_date_t ON start_date_t.name_start = end_date_t.name_end
WHERE score_end-score_start < 0
lets say you have a table with date_value, sum_value
Then it should be something like that:
select t.date_value,sum_value,
sum_value - COALESCE((
select top 1 sum_value
from tmp_num
where date_value > t.date_value
order by date_value
),0) as sum_change
from tmp_num as t
order by t.date_value
The following uses a "trick" in MySQL that I don't really like using, because it turns the score into a string and then back into a number. But, it is an easy way to get what you want:
select t.name, (lastscore - firstscore) as diff
from (select t.name,
substring_index(group_concat(score order by date asc), ',', 1) as firstscore,
substring_index(group_concat(score order by date desc), ',', 1) as lastscore
from table t
group by t.name
) t
where lastscore - firstscore < 0;
If MySQL supported window functions, such tricks wouldn't be necessary.
I have a table like this:
ID_____StartDate_____EndDate
----------------------------
1______05/01/2012___02/03/2013
2______06/30/2013___07/12/2013
3______02/17/2010___02/17/2013
4______12/10/2012___11/16/2013
I'm trying to get a count of the ID's that were active during each year. If the ID was active for multiple years, it would be counted multiple times. I don't want to "hardcode" years into my query because the data is over many many multiple years. (i.e. can't use CASE YEAR(StartDate) WHEN x then y or IF...
Desired Result from the table above:
YEAR_____COUNT
2010_____1
2011_____1
2012_____3
2013_____4
I've tried:
SELECT COUNT(ID)
FROM table
WHERE (DATE_FORMAT(StartDate, '%Y-%m') BETWEEN '2013-01' AND '2013-12'
OR DATE_FORMAT(EndDate, '%Y-%m') BETWEEN '2013-01' AND '2013-12')
of course this only is for the year 2013. I also tried:
SELECT YEAR(StartDate) AS 'Start Year', YEAR(EndDate) AS 'End Year', COUNT(id)
FROM table
WHERE StartDate IS NOT NULL
GROUP BY YEAR(StartDate);
though this gave me just those that started in a given year.
Assuming that there is an auxiliary table that contains consecutive numbers from 1 .. to X (where X must be grather than possible number of years in the table):
create table series( x int primary key auto_increment );
insert into series( x )
select null from information_schema.tables;
then the query might look like:
SELECT years.year, count(*)
FROM (
SELECT mm.min_year + s.x - 1 as year
FROM (
SELECT min( year( start_date )) min_year,
max( year( end_date )) max_year
FROM tab
) mm
JOIN series s
ON s.x <= mm.max_year - mm.min_year + 1
GROUP BY mm.min_year + s.x - 1
) years
JOIN tab
ON years.year between year( tab.start_date )
and year( tab.end_date )
GROUP BY years.year
;
see a demo: http://www.sqlfiddle.com/#!2/f49ab/14
I have a query that works correctly to pull a series of targets and total hours worked for company A. I would like to run the exact same query for company B and join them on a common date, which happens to be grouped by week. My current query:
SELECT * FROM (
SELECT org, date,
( SELECT SUM( target ) FROM target WHERE org = "companyA" ) AS companyA_target,
SUM( hours ) AS companyA_actual
FROM time_management_system
WHERE org = "companyA"
GROUP BY WEEK( date )
ORDER BY DATE
) q1
LEFT JOIN (
SELECT org, date,
( SELECT SUM( target ) FROM target WHERE org = "companyB" ) AS companyB_target,
SUM( hours ) AS companyB_actual
FROM time_management_system
WHERE org = "companyB"
GROUP BY WEEK( date )
ORDER BY DATE
) q2
ON q1.date = q2.date
The results show all of the dates / information of companyA, however companyB only shows sporadic data. Separately, the two queries will show the exact same set of dates, just with different information in the 'target' and 'actual' columns.
companyA 2012-01-28 105.00 39.00 NULL NULL NULL NULL
companyA 2012-02-05 105.00 15.00 NULL NULL NULL NULL
companyA 2012-02-13 105.00 60.50 companyB 2012-02-13 97.50 117.50
Any idea why I'm not getting all the information for companyB?
As a side note, would anybody be able to point in the direction of converting each row's week value into a column? With companyA and companyB as the only two rows?
I appreciate all the help! Thanks.
WITH no date apparent in the target table, the summation will be constant across all weeks. So, I have performed a pre-query for only those "org" values of company A and B with a group by. This will ensure only 1 record per "org" so you don't get a Cartesian result.
Then, I am querying the time_management_system ONCE for BOTH companies. Within the field computations, I am applying an IF() to test the company value and apply when correct. The WEEK activity is the same for both in the final result, so I don't have to do separately and join. This also prevents the need of having the date column appear twice. I also don't need to explicitly add the org column names as the final column names reflect that.
SELECT
WEEK( tms.date ) as GrpWeek,
IF( tms.org = "companyA", TargetSum.CompTarget, 00000.00 )) as CompanyATarget,
SUM( IF( tms.org = "companyA", tms.hours, 0000.00 )) as CompanyAHours,
IF( tms.org = "companyB", TargetSum.CompTarget, 00000.00 )) as CompanyBTarget,
SUM( IF( tms.org = "companyB", tms.hours, 000.00 )) as CompanyBHours
from
Time_Management_System tms
JOIN ( select
t.org,
SUM( t.target ) as CompTarget
from
Target T
where
t.org in ( "companyA", "companyB" )
group by
t.org ) as TargetSums
ON tms.org = TargetSums.org
where
tms.org in ( "companyA", "companyB" )
group by
WEEK( tms.date )
order by
WEEK( tms.date )
Both of your subqueries are wrong.
Either you want this:
SELECT
org,
WEEK(date),
( SELECT SUM( target ) FROM target WHERE org = "companyB" ) AS companyB_target,
SUM( hours ) AS companyB_actual
FROM time_management_system
WHERE org = "companyB"
GROUP BY WEEK( date )
Or else you want this:
SELECT
org,
date,
( SELECT SUM( target ) FROM target WHERE org = "companyB" ) AS companyB_target,
SUM( hours ) AS companyB_actual
FROM time_management_system
WHERE org = "companyB"
GROUP BY date
The way you are doing it now is not correctly formed SQL. In pretty much any other database your query would fail immediately with an error. MySQL is more lax and runs the query but gives indeterminate results.
GROUP BY and HAVING with Hidden Columns