I've been racking my brain about how to do this in one query without PHP code.
In a nutshell, I have a table that records email activity. For the sake of this example, here is the data:
recipient_id activity date
1 delivered 2011-08-30
1 open 2011-08-31
2 delivered 2011-08-30
3 delivered 2011-08-24
3 open 2011-08-30
3 open 2011-08-31
The goal: I want to display to users a single number that tells how many recipients open their email within 24 hours.
E.G. "Users that open their email within 24 hours: 13 Readers"
In the case of the sample data, above, the value would be "1". (Recipient one was delivered an email and opened it the next day. Recipient 2 never opened it and recipient 3 waited 5 days.)
Can anyone think of a way to express the goal in a single query?
Reminder: In order to count, the person must have a 'delivered' tag and at least one 'open' tag. Each 'open' tag only counts once per recipient.
** EDIT ** Sorry, I'm using MySQL
Here is a version in mysql.
select count(distinct recipient_id)
from email e1
where e1.activity = 'delivered'
and exists
(select * from email e2
where e1.recipient_id = e2.recipient_id
and e2.activity = 'open'
and datediff(e2.action_date,e1.action_date) <= 1)
The basic principle is that you want to find a delivered row for a recipient that also has an open within 24 hours.
The datediff() is a good way to do the date arithmetic in mysql -- other dbs will vary on exact methods for this step. The rest of the sql will work anywhere.
SQLFiddle here: http://sqlfiddle.com/#!2/c9116/4
Untested, but should work ;) Don't know which SQL dialect you use, so I've used TSQL DATEDIFF function.
select distinct opened.recipient_id -- or count(distinct opened.recipient_id) if you want to know number
from actions as opened
inner join actions as delivered
on opened.recipient_id = delivered.recipient_id and delivered.activity = 'delivered'
where opened.activity = 'open' and DATEDIFF(day, delivered.date, opened.date) <= 1
Edit: I'd confused opened with delivered - now replaced.
Assumptions: MySql, table is called "TABLE"
Ok, I am not 100% on this, because I don't have a copy of the table to run it against, but I think that you could do something like this:
SELECT COUNT(DISTINCT t1.recipient_id) FROM TABLE t1
INNER JOIN TABLE t2 ON t1.recipient_id = t2.recipient_id AND t1.activity != t2.activity
WHERE t1.activity in ('delivered', 'open') AND t2.activity in ('delivered', 'open')
AND ABS(DATEDIFF(t1.date, t2.date)) = 1
Basically, you are joining a table onto itself, where the activities don't match, but recipient_ids do, and the status is either 'delivered' or 'open'. What you would end up getting, is a result that looks like this:
1 delivered 2011-08-30 1 open 2011-08-31
You are then doing a diff between the two dates (with an absolute value, because we don't know which order they will be in) and making sure that it is equal to 1 (or 24 hours).
Related
I have two tables in a CRM application that I am trying to build.
"Contacts" Table:
id
Name
ContactFrequency (in days)
1
John
7
2
Pete
30
"Events" Table:
id
Contacts_id
Description
Unix_Timestamp
1
1
Sent John an email
1609667504
2
1
Gave John a call
1609645455
1
2
Sent Pete a letterl
1609666755
The "ContactFrequency" is how often I should call that client to stay in touch. Each entry in Events is a call log with a UNIX timestamp. I want to generate a list of clients who need to be called in the next X number of days (or whose next contacts have already passed and are overdue), such as the following (timestamps are completely arbitrary in my examples):
Client
Next Contact Due on (Timestamp)(Ordered by this column)
Pete
1609645352
John
1609634342
How would I do this with a query? I can't wrap my head around it.
Formally:
SELECT Contacts.Name Client,
COALESCE(FROM_UNIXTIME(MAX(Events.Unix_Timestamp)) + INTERVAL Contacts.ContactFrequency DAY, CURRENT_TIMESTAMP) NextContactDueOn
FROM Contacts
LEFT JOIN Events ON Contacts.id = Events.Contacts_id
GROUP BY Client
ORDER BY NextContactDueOn DESC
I have very limited experience with MySQL past standard queries, but when it comes to joins and relations between multiple tables I have a bit of an issue.
I've been tasked with creating a job that will pull a few values from a mysql database every 15 minutes but the info it needs to display is pulled from multiple tables.
I have worked with it for a while to figure out the relationships between everything for the phone system and I have discovered how I need to pull everything out but I'm trying to find the right way to create the job to do the joins.
I'm thinking of creating a new table for the info I need, with columns named as:
Extension | Total Talk Time | Total Calls | Outbound Calls | Inbound Calls | Missed Calls
I know that I need to start with the extension ID from my 'user' table and match it with 'extensionID' in my 'callSession'. There may be multiple instances of each extensionID but each instance creates a new 'UniqueCallID'.
The 'UniqueCallID' field then matches to 'UniqueCallID' in my 'CallSum' table. At that point, I just need to be able to say "For each 'uniqueCallID' that is associated with the same 'extensionID', get the sum of all instances in each column or a count of those instances".
Here is an example of what I need it to do:
callSession Table
UniqueCallID | extensionID |
----------------------------
A 123
B 123
C 123
callSum table
UniqueCallID | Duration | Answered |
------------------------------------
A 10 1
B 5 1
C 15 0
newReport table
Extension | Total Talk Time | Total Calls | Missed Calls
--------------------------------------------------------
123 30 3 1
Hopefully that conveys my idea properly.
If I create a table to hold these values, I need to know how I would select, join and insert those things based on that diagram but I'm unable to construct the right query/statement.
You simply JOIN the two tables, and do a group by on the extensionID. Also, add formulas to summarize and gather the info.
SELECT
`extensionID` AS `Extension`,
SUM(`Duration`) AS `Total Talk Time`,
COUNT(DISTINCT `UniqueCallID`) as `Total Calls`,
SUM(IF(`Answered` = 1,0,1)) AS `Missed Calls`
FROM `callSession` a
JOIN `callSum` b
ON a.`UniqueCallID` = b.`UniqueCallID`
GROUP BY a.`extensionID`
ORDER BY a.`extensionID`
You can use a join and group by
select
a.extensionID
, sum(b.Duration) as Total_Talk_Time
, count(b.Answered) as Total_Calls
, count(b.Answered) -sum(b.Answered) as Missed_calls
from callSession as a
inner join callSum as b on a.UniqueCallID = b.UniqueCallID
group by a.extensionID
This should do the trick. What you are being asked to do is to aggregate the number of and duration of calls. Unless explicitly requested, you do not need to create a new table to do this. The right combination of JOINs and AGGREGATEs will get the information you need. This should be pretty straightforward... the only semi-interesting part is calculating the number of missed calls, which is accomplished here using a "CASE" statement as a conditional check on whether each call was answered or not.
Pardon my syntax... My experience is with SQL Server.
SELECT CS.Extension, SUM(CA.Duration) [Total Talk Time], COUNT(CS.UniqueCallID) [Total Calls], SUM(CASE CS.Answered WHEN '0' THEN SELECT 1 ELSE SELECT 0 END CASE) [Missed Calls]
FROM callSession CS
INNER JOIN callSum CA ON CA.UniqueCallID = CS.UniqueCallID
GROUP BY CS.Extension
I've a table with a structure something like this,
Device | paid | time
abc 1 2 days ago
abc 0 1 day ago
abc 0 5 mins ago
Is it possible to write a query that checks the paid column on all the rows where Device = abc and then outputs the most recent two rows that different. Basically, something like an if statement saying if row 1 = 1 and row 2 = 0 output that but only if it's the most recent two columns that are different. For example, in this case, the first and second row. The table is being updated whenever a user changes from a free to paid account etc. It is also updated in different columns for different reasons hence the duplicate 0s for example.
I know this would probably be done better by having another table altogether and updating that every time the user switches account type, but is there any way to make this work?
Thanks
Example:
http://rextester.com/MABU7860 need further testing on edge cases but this seems to work.
SELECT A.*, B.*
FROM SQLfoo A
INNER JOIN SQLFoo B
on A.Device = B.Device
and A.mTime < B.mTime
WHERE A.Paid <> B.Paid
and A.device = 'abc'
ORDER BY B.mTime Desc, A.MTime Desc
LIMIT 1
By performing a self join we on the devices where the time from one table is less than the time from the next table (thus the two records will never matach and we only get the reuslts one way) and we order by those times descending, the highest times appear first in the result since we limit by a single device we don't need to concern ourselves with the devices. We then just need compare the paid from one source to the paid in the 2nd source and return the first result encountered thus limit 1.
Or using user variables
http://rextester.com/TWVEVX7830
in other engines one might accomplish this task by performing the join as in above, assigning a row number partitioned by the device and then simply return all those row_numbers with a value of 1; which would be the earliest date discrepency.
Use LIMIT to limit the number of record on mysql:
http://www.mysqltutorial.org/mysql-limit.aspx
In your case, use LIMIT 2
and then put the 2 record that you just select into an array, then compare the array if the value is different. If they are different then print
I have a database table that contains one or more entries for each patient. These contain free text and additional information about a test request. Querying on a patient would for example return:-
TestID PatientID RequestMade FreeText
1 23 13/12/2015 11:00:00 Feeling breathless
1125 23 07/04/2016 09:31:15 Unexplained fractures
2556 23 04/12/2016 16:20:21 Check liver function – on statins
When viewing test results I have to pull up the request information relating to the test which will be the last one prior to the test. The results have a TestDate so a TestDate of '13/04/2016 14:21:30' should display the request of '07/04/2016 09:31:15'. I am unsure how to code this efficiently as returning every entry for a patient and doing a date comparison on each one seems not the best way to tackle it.
If you want the one test before another test for a single patient and the test you are looking for only appears once, then you can do this with a single query as:
select t.*
from tests t
where t.patientid = 23 and
t.requestmade < (select t2.requestmade
from tests t2
where t2.patientid = t.patientid and
t2.testid = ?
)
order by t.requestmade desc
limit 1;
I have a table "audit" with a "description" column, a "record_id" column and a "record_date" column. I want to select only those records where the description matches one of two possible strings (say, LIKE "NEW%" OR LIKE "ARCH%") where the record_id in each of those two matches each other. I then need to calculate the difference in days between the record_date of each other.
For instance, my table may contain:
id description record_id record_date
1 New Sub 1000 04/14/13
2 Mod 1000 04/14/13
3 Archived 1000 04/15/13
4 New Sub 1001 04/13/13
I would want to select only rows 1 and 3 and then calculate the number of days between 4/15 and 4/14 to determine how long it took to go from New to Archived for that record (1000). Both a New and an Archived entry must be present for any record for it to be counted (I don't care about ones that haven't been archived). Does this make sense and is it possible to calculate this in a SQL query? I don't know much beyond basic SQL.
I am using MySQL Workbench to do this.
The following is untested, but it should work asuming that any given record_id can only show up once with "New Sub" and "Archived"
select n.id as new_id
,a.id as archive_id
,record_id
,n.record_date as new_date
,a.record_date as archive_date
,DateDiff(a.record_date, n.record_date) as days_between
from audit n
join audit a using(record_id)
where n.description = 'New Sub'
and a.description = 'Archieved';
I changed from OR to AND, because I thought you wanted only the nr of days between records that was actually archived.
My test was in SQL Server so the syntax might need to be tweaked slightly for your (especially the DATEDIFF function) but you can select from the same table twice, one side grabbing the 'new' and one grabbing the 'archived' then linking them by record_id...
SELECT
newsub.id,
newsub.description,
newsub.record_date,
arc.id,
arc.description,
arc.record_date,
DATEDIFF(day, newsub.record_date, arc.record_date) AS DaysBetween
FROM
foo1 arc
, foo1 newsub
WHERE
(newsub.description LIKE 'NEW%')
AND
(arc.description LIKE 'ARC%')
AND
(newsub.record_id = arc.record_id)