Hi I am calculating CRentention and I want to calculate the retention for 1day, 3 day and 7 days, but I have made three queries, can somebody please tell me how I can write thee in one query.
Please help!
The simple way to combine multiple queries is generally a join. If you take each of your queries and turn them into subqueries, then join by date, this should give you the results you want.
As in:
SELECT one_day.activity_date as activity_date,
one_day.signed_up_users, one_day.logged_in_users, one_day.retention_pct,
three_day.signed_up_users, three_day.logged_in_users, three_day.retention_pct,
seven_day.signed_up_users, seven_day.logged_in_users, seven_day.retention_pct
FROM (SELECT ... ) as one_day
JOIN (SELECT ... ) as three_day
ON one_day.activity_date = three_day.activity_date
JOIN (SELECT ... ) as seven_day
ON one_day.activity_date = seven_day.activity_date
You also can use IF() clauses to do this in a non-joined fashion. You can create a column that is 1 if in the 1 day count and 0 otherwise, then compute the sum when you aggregate.
Related
I keep running in to the same problem over and over again, hoping someone can help...
I have a large table with a category column that has 28 entries for donkey breed, then I'm counting two specific values grouped by each of those categories in subqueries like this:
WITH totaldonkeys AS (
SELECT donkeybreed,
COUNT(*) AS total
FROM donkeytable1
GROUP BY donkeybreed
)
,
sickdonkeys AS (
SELECT donkeybreed,
COUNT(*) AS totalsick
FROM donkeytable1
JOIN donkeyhealth on donkeytable1.donkeyid = donkeyhealth.donkeyid
WHERE donkeyhealth.sick IS TRUE
GROUP BY donkeybreed
)
,
It's my goal to end up with a table that has primarily the percentage of sick donkeys for each breed but I always end up struggling like hell with the problem of not being able to group by without using an aggregate function which I cannot do here:
SELECT (CAST(sickdonkeys.totalsick AS float) / totaldonkeys.total) * 100 AS percentsick,
totaldonkeys.donkeybreed
FROM totaldonkeys, sickdonkeys
GROUP BY totaldonkeys.donkeybreed
When I run this I end up with 28 results for each breed of donkey, one correct I believe but obviously hundreds of useless datapoints.
I know I'm probably being really dumb here but I keep hitting in to this same problem again and again with new donkeydata, I should obviously be structuring the whole thing a new way because you just can't do this final query without an aggregate function, I think I must be missing something significant.
You can easily count the proportion that are sick in the donkeyhealth table
SELECT d.donkeybreed,
AVG( (dh.sick)::int ) AS proportion_sick
FROM donkeytable1 d JOIN
donkeyhealth dh
ON d.donkeyid = dh.donkeyid
GROUP BY d.donkeybreed
I am new to SQL and have had pretty good luck figuring things out thus far but I am missing something in this query:
The question is how to return a distinct count from two columns using another column and the criteria if the value is greater than 0.
I have tried IF and AND operators (My current query returns a 0 not an error, and it works when only using one .shp criteria)
select count (distinct ti.TO_ADDRESS)
from ti
where ti.input_id = 'xxx_029_01z_c_zzzzbab_ecrm.shp'
and ti.input_id = 'xxx_030_01z_c_zzzzbab_ecrm.shp'
and ti.OPENED>0;
Thanks so much!!
I think you want two levels of aggregation:
select count(*)
from (select ti.TO_ADDRESS
from ti
where ti.input_id in ('xxx_029_01z_c_zzzzbab_ecrm.shp', 'xxx_030_01z_c_zzzzbab_ecrm.shp') and
ti.OPENED > 0
group by ti.TO_ADDRESS
having count(distinct ti.input_id) = 2 -- has both of them
) ti;
I need to figure out how to eliminate older revisions from my query's results, my database stores orders as 'Q000000' and revisions have an appended '-number'. My query currently is as follows:
SELECT DISTINCT Estimate.EstimateNo
FROM Estimate
INNER JOIN EstimateDetails ON EstimateDetails.EstimateID = Estimate.EstimateID
INNER JOIN EstimateDoorList ON EstimateDoorList.ItemSpecID = EstimateDetails.ItemSpecID
WHERE (Estimate.SalesRepID = '67' OR Estimate.SalesRepID = '61') AND Estimate.EntryDate >= '2017-01-01 00:00:00.000' AND EstimateDoorList.SlabSpecies LIKE '%MDF%'
ORDER BY Estimate.EstimateNo
So for instance, the results would include:
Q120455-10
Q120445-11
Q121675-2
Q122361-1
Q123456
Q123456-1
From this, I need to eliminate 'Q120455-10' because of the presence of '-11' for that order, and 'Q123456' because of the presence of the '-1' revision. I'm struggling greatly with figuring out how to do this, my immediate thought was to use case statements but I'm not sure what is the best way to implement them and how to filter. Thank you in advance, let me know if any more information is needed.
First you have to parse your EstimateNo column into sequence number and revision number using CHARINDEX and SUBSTRING (or STRING_SPLIT in newer versions) and CAST/CONVERT the revision to a numeric type
SELECT
SUBSTRING(Estimate.EstimateNo,0,CHARINDEX('-',Estimate.EstimateNo)) as [EstimateNo],
CAST(SUBSTRING(Estimate.EstimateNo,CHARINDEX('-',Estimate.EstimateNo)+1, LEN(Estimate.EstimateNo)-CHARINDEX('-',Estimate.EstimateNo)+1) as INT) as [EstimateRevision]
FROM
...
You can then use
APPLY - to select TOP 1 row that matches the EstimateNo or
Window function such as ROW_NUMBER to select only records with row number of 1
For example, using a ROW_NUMBER would look something like below:
SELECT
ROW_NUMBER() OVER(PARTITION BY EstimateNo ORDER BY EstimateRevision DESC) AS "LastRevisionForEstimate",
-- rest of the needed columns
FROM
(
-- query above goes here
)
You can then wrap the query above in a simple select with a where predicate filtering out a specific value of LastRevisionForEstimate, for instance
SELECT --needed columns
FROM -- result set above
WHERE LastRevisionForEstimate = 1
Please note that this is to a certain extent, pseudocode, as I do not have your schema and cannot test the query
If you dislike the nested selects, check out the Common Table Expressions
I'm using Access (I normally use SQL Server) for a little job, and I'm getting "enter parameter value" for Night.NightId in the statement below that has a subquery within a subquery. I expect it would work if I wasn't nesting it two levels deep, but I can't think of a way around it (query ideas welcome).
The scenario is pretty simple, there's a Night table with a one-to-many relationship to a Score table - each night normally has 10 scores. Each score has a bit field IsDouble which is normally true for two of the scores.
I want to list all of the nights, with a number next to each representing how many of the top 2 scores were marked IsDouble (would be 0, 1 or 2).
Here's the SQL, I've tried lots of combinations of adding aliases to the column and the tables, but I've taken them out for simplicity below:
select Night.*
,
( select sum(IIF(IsDouble,1,0)) from
(SELECT top 2 * from Score where NightId=Night.NightId order by Score desc, IsDouble asc, ID)
) as TopTwoMarkedAsDoubles
from Night
This is a bit of speculation. However, some databases have issues with correlation conditions in multiply nested subqueries. MS Access might have this problem.
If so, you can solve this by using aggregation with a where clause that chooses the top two values:
select s.nightid,
sum(IIF(IsDouble, 1, 0)) as TopTwoMarkedAsDoubles
from Score as s
where s.id in (select top 2 s2.id
from score as s2
where s2.nightid = s.nightid
order by s2.score desc, s2.IsDouble asc, s2.id
)
group by s.nightid;
If this works, it is a simply matter to join Night back in to get the additional columns.
Your subquery can only see one level above it. so Night.NightId is totally unknown to it hence why you are being prompted to enter a value. You can use a Group By to get the value you want for each NightId then correlate that back to the original Night table.
Select *
From Night
left join (
Select N.NightId
, sum(IIF(S.IsDouble,1,0)) as [Number of Doubles]
from Night N
inner join Score S
on S.NightId = S.NightId
group by N.NightId) NightsWithScores
on Night.NightId = NightsWithScores.NightId
Because of the IIF(S.IsDouble,1,0) I don't see the point is using top.
Working on a query to return the average time from when an employee begins his/her shift and then arrives at the first home (this DB assumes they are salesmen).
What I have:
SELECT l.OFFICE_NAME, crew.EMPLOYEE_NAME, //avg(first arrival time)
FROM LOCAL_OFFICE l, CREW_WORK_SCHEDULE crew,
WHERE l.LOCAL_OFFICE_ID = crew1.LOCAL_OFFICE_ID
You can see the AVG() command is commented out, because I know the time that they arrive at work, and the time they get to the first house, and can find the value using this:
(SELECT MIN(c.ARRIVE)
FROM ORDER_STATUS c
WHERE c.USER_ID = crew.CREW_ID)
-(SELECT START_TIME
FROM CREW_SHIFT_CODES
WHERE WORK_SHIFT_CODE = crew.WORK_SHIFT_CODE)
Would the best way be to simply put the above into the the AVG() parentheses? Just trying to learn the best methods to create queries. If you want more info on any of the tables, etc. just ask, but hopefully they're all named so you know what they're returning.
As per my comment, the example you gave would only return one record to the AVG function, and so not do very much.
If the sub-query was returning multiple records, however, your suggestion of placing the sub-query inside the AVG() would work...
SELECT
AVG((SELECT MIN(sub.val) FROM sub WHERE sub.id = main.id GROUP BY sub.group))
FROM
main
GROUP BY
main.group
(Averaging a set of minima, and so requiring two levels of GROUP BY.)
In many cases this gives good performance, and is maintainable. But sometimes the sub-query grows large, and it can be better to reformat it using an inline view...
SELECT
main.group,
AVG(sub_query.val)
FROM
main
INNER JOIN
(
SELECT
sub.id,
sub.group,
MIN(sub.val) AS val
FROM
sub
GROUP BY
sub.id
sub.group
)
AS sub_query
ON sub_query.id = main.id
GROUP BY
main.group
Note: Although this looks as though the inline view will calculate a lod of values that are not needed (and so be inefficient), most RDBMS optimise this so only the required records get processes. (The optimiser knows how the inner query is being used by the outer query, and builds the execution plan accordingly.)
Don't think of subqueries: they're often quite slow. In effect, they are row by row (RBAR) operations rather than set based
join all the table together
I've used a derived table to calculate the 1st arrival time
Aggregate
Soemthing like
SELECT
l.OFFICE_NAME, crew.EMPLOYEE_NAME,
AVG(os.minARRIVE - cs.START_TIME)
FROM
LOCAL_OFFICE l
JOIN
CREW_WORK_SCHEDULE crew On l.LOCAL_OFFICE_ID = crew1.LOCAL_OFFICE_ID
JOIN
CREW_SHIFT_CODES cs ON cs.WORK_SHIFT_CODE = crew.WORK_SHIFT_CODE
JOIN
(SELECT MIN(ARRIVE) AS minARRIVE, USER_ID
FROM ORDER_STATUS
GROUP BY USER_ID
) os ON oc.USER_ID = crew.CREW_ID
GROUP B
l.OFFICE_NAME, crew.EMPLOYEE_NAME
This probably won't give correct data because of the minARRIVE grouping: there isn't enough info from ORDER_STATUS to show "which day" or "which shift". It's simply "first arrival for that user for all time"
Edit:
This will give you average minutes
You can add this back to minARRIVE using DATEADD, or change to hh:mm with some %60 (modul0) and /60 (integer divide
AVG(
DATEDIFF(minute, os.minARRIVE, os.minARRIVE)
)