I have a set of MySQL data similar to the following:
| id | type | start | end |
===============================================================
| 1 | event | 2011-11-01T00:00:00 | 2012-01-02T00:00:00 |
| 2 | showing | 2012-11-04T00:00:00 | 2012-11-04T00:00:00 |
| 3 | conference | 2012-12-01T00:00:00 | 2012-12-04T00:00:00 |
| 4 | event2 | 2012-01-01T00:00:00 | 2012-01-01T00:00:00 |
I want to retrieve events within a certain date range, but I also want to return individual results for each row that has a time span of more than one day. What's the best way to achieve this?
EDIT: In other words, I want to return two results from the event row, four results from the conference row and a single result for all the others.
Any ideas would be greatly appreciated.
Try this statement:
SELECT * FROM table
WHERE START BETWEEN '2012-01-01' AND '2012-01-03'
OR END BETWEEN '2012-01-01' AND '2012-01-03'
OR TO_DAYS(end) - TO_DAYS(start) > 1
I have created it for testing on SQL Fiddle
Related
I am trying to get aggregate sums for days between certain dates. I have managed to use DATEDIFF to find the number of days, but cannot find a way to add them.
Here is what I would like the table to look like. Please note that dates are in UK format and days counted include both Start and End date. I also have removed weekends so that this only includes weekdays:
User | txtStartDate | txtEndDate | Days | Days Total
-------------------------------------------------------------------------
1 | 04/01/18 | 05/01/18 | 2 | 2
1 | 09/01/18 | 12/01/18 | 4 | 6
1 | 22/01/18 | 31/01/18 | 8 | 14
-------------------------------------------------------------------------
2 | 11/01/18 | 12/01/18 | 2 | 2
2 | 18/01/18 | 18/01/18 | 1 | 3
-------------------------------------------------------------------------
TOTAL | 17
I am using this code to calculate the days:
=DateDiff(DateInterval.day, Fields!txtStartDate.Value, Fields!txtEndDate.Value)+1)
-(DateDiff(DateInterval.WeekOfYear, Fields!txtStartDate.Value, Fields!txtEndDate.Value)*2)
and have tried putting this in =SUM() to calculate the total but this does not work.
Any help would be greatly appreciated.
Thanks
Rob
You need to use RunningValue
You might get a syntax error here
=RunningValue(DateDiff(DateInterval.day, Fields!txtStartDate.Value, Fields!txtEndDate.Value)+1)
-(DateDiff(DateInterval.WeekOfYear, Fields!txtStartDate.Value, Fields!txtEndDate.Value)*2)
,sum
,"DataSet1") --enter the scope here or `nothing`
I need to skip results with high price per day. I've got a table like this:
+------+-------------+-------+
| days | return_date | value |
+------+-------------+-------+
| 2 | 2017-12-27 | 15180 |
| 3 | 2017-12-28 | 14449 |
| 4 | 2017-12-29 | 13081 |
| 5 | 2017-12-30 | 11203 |
| 6 | 2017-12-31 | 9497 |
| 6 | 2017-12-31 | 9442 |
+------+-------------+-------+
How can I print only the lowest price for 6 days (9442 in this example).
We can use a GROUP BY clause and an aggregate function. For example:
SELECT t.days
, t.return_date
, MIN(t.value) AS min_value
FROM mytable t
GROUP
BY t.days
, t.return_date
This doesn't really "skip" rows. It accesses all the rows that satisfy the conditions in the WHERE clause (in this example, every row in the table). Then MySQL collapses rows into groups (in this example, rows with identical values of days and return_date get put into a group. The MIN(t.value) aggregate function selects out the minimum (lowest) value out of the group.
The query above is just an example of one approach of satisfying a particular specification.
I have this table structure:
// mytable
+----+------+-------+-------------+
| id | type | score | unix_time |
+----+------+-------+-------------+
| 1 | 1 | 5 | 1463508841 |
| 2 | 1 | 10 | 1463508842 |
| 3 | 2 | 5 | 1463508843 |
| 4 | 1 | 5 | 1463508844 |
| 5 | 2 | 15 | 1463508845 |
| 6 | 1 | 10 | 1463508846 |
+----+------+-------+-------------+
And here is my query:
SELECT SUM(score), unix_time
FROM mytable
WHERE 1
GROUP BY type
And here is the output:
+-------+-------------+
| score | unix_time |
+-------+-------------+
| 30 | 1463508841 |
| 20 | 1463508843 |
+-------+-------------+
Ok, all fine .. Just there is a thing: Professional people suggest me to write unix_time into GROUP BY. They believe doing that is the base of grouping and aggregate function.
Well why really should I write a (almost) unique column into GROUP BY? If I do that then each row will be a separated group and there will be a lot of extra rows which are useless:
+-------+-------------+
| score | unix_time |
+-------+-------------+
| 30 | 1463508841 |
| 30 | 1463508842 |
| 20 | 1463508843 |
| 30 | 1463508844 |
| 20 | 1463508845 |
| 30 | 1463508846 |
+-------+-------------+
See? There is a lot of extra rows. So why doing that is an standard thing? Why everybody tell me MySQL does work without doing that but no database else doesn't .. Well I really don't understand why should I do that ..!
May please someone make it clear for me and explain me how GROUP BY works exactly? Is that different than my understanding?
Not having unix_time in the GROUP BY clause is a non-standard MySQL hack that I would totally stay away from. The values for unix_type across all the rows with the same type are completely different. How do you know which unix_time should appear?
In your example, you seem perfectly content to use a completely arbitrary value of unix_time per group.
However this is a recipe for disaster. What does it even mean to pick some totally arbitrary value from a group? What if the unix_times were spread out by days or weeks or even years? Which one would you take then?
The reason the pros are telling you to put it in the group by clause is so that the result makes sense! Another approach is to leave unix_time out of the select completely, as the result you are getting shouldn't be relied upon.
Maybe you need something like this:
SELECT type,
SUM(score) as sum_of_score,
MIN(unix_time) as start_unix_time,
MAX(unix_time) as end_unix_time
FROM mytable
WHERE 1
GROUP BY type
I have 3 tables in MySQL:
1) page (id, title)
2) visitor (id, name)
3) page_visit (page_id, visitor_id, timestamp_of_visit)
Visitors can visit pages multiple times, across several days. Hence, while we will have one row for a page, and one row for a visitor, we can have several page_visit rows, each with a timestamp of the visit.
I'm trying to find the number of unique visitors, by week. I know how to get the 'by week count' query for non-uniques (i.e. 'how many visitors did I see each week'). I'm not sure how to pick the unique visitors by week, though, with the visitor showing up on the list ONLY the first time they are ever seen.
----------- ----------- ----------------------------
| page | | visitor | | page_visit |
----------- ----------- ----------------------------
|id |title| |id |name | |pid|vid|timestamp of visit|
----------- ----------- ----------------------------
| 1 | p1 | | 1 | v1 | | 1 | 1 | 02-18-2016:08:30 |
| 2 | p2 | | 2 | v2 | | 1 | 1 | 02-18-2016:10:00 |
| 3 | p3 | | 3 | v3 | | 1 | 3 | 02-20-2016:23:45 |
| 4 | p4 | | 4 | v4 | | 2 | 3 | 02-22-2016:07:30 |
| 5 | p5 | | 5 | v5 | | 3 | 1 | 02-23-2016:08:30 |
| 6 | p6 | | 6 | v6 | | 3 | 6 | 02-24-2016:09:30 |
What the result set should show:
------------------------
| results |
------------------------
| Week of | Net new |
------------------------
| 02-15-2016 | 2 |
| 02-22-2016 | 1 |
As mentioned, I can figure out how to show ALL visitors by week. I'm not sure how to get the unique visitors.
I tried doing a min(timestamp of visit), but, based on where I tried it, it returned the lowest timestamp across all rows (understandably...).
Any help would be much appreciated!
This is a tricky question when you first encounter it. It requires two levels of aggregation. The first gets the first visit for each visitor, the second summarizes by time. The following does the summary by day:
select date(minvd), count(*) as numvisitors
from (select vid, min(visitdate) as minvd
from page_visit pv
group by vid
) v
group by date(minvd)
order by date(minvd);
Translating to weeks is always a bit tricky -- do they begin on Mondays? End on Saturdays? On Fridays? (I've seen all of these.) However, the above is additive, so you can just add all the values for a given week to get your value.
In case you want to do this without a subquery:
SELECT
<week>,
COUNT(DISTINCT PV.vid)
FROM
Page_Visit PV
LEFT OUTER JOIN Page_Visit PV2 ON
PV2.vid = PV.vid AND
PV2.visit_date < PV.visit_date
WHERE
PV2.vid IS NULL
GROUP BY
<week>
As Gordon mentions, how you determine the week can be tricky. Just add in that calculation where you see <week>. Personally, I like to use a Calendar table for that kind of functionality, but it's up to you. You can run any expressions directly against PV.visit_date to determine it.
I have a database like below
+------------+---------------------------------------+--------+
| sender | subject | day |
+------------+---------------------------------------+--------+
| Darshana | Re: [Dev] [Platform] Build error | Monday |
| Dushan A | (MOLDOVADEVDEV-49) GREG Startup Error | Monday |
+------------+---------------------------------------+--------+
I want to get the result using the above table. It should check if the subject contains the given word then add one to the that word column for a given day.
|Day | "Dev" | "startup"|
+---------+------------+----------+
| Monday | 1 | 2 |
| Friday | 0 | 3 |
I was thought of using DECODE function but I couldn't get the expected result.
You can do this with conditional aggregation:
select day, sum(subject like '%Dev%') as Dev,
sum(subject like '%startup%') as startup
from table t
group by day;