In MS Access, I have a query where I want to use a column in the outer query as a condition in the inner query:
SELECT P.FirstName, P.LastName, Count(A.attendance_date) AS CountOfattendance_date,
First(A.attendance_date) AS FirstOfattendance_date,
(SELECT COUNT (*)
FROM(SELECT DISTINCT attendance_date
FROM tblEventAttendance AS B
WHERE B.event_id=8
AND B.attendance_date >= FirstOfattendance_date)
) AS total
FROM tblPeople AS P INNER JOIN tblEventAttendance AS A ON P.ID = A.people_id
WHERE A.event_id=8
GROUP BY P.FirstName, P.LastName
;
The key point is FirstOfattendance_date - I want the comparison deep in the subselect to use the value in each iteration of the master select. Obviously this doesn't work, it asks me for the value of FirstOfattendance_date when I try to run it.
I'd like to do this without resorting to VB code... any ideas?
How about:
SELECT
p.FirstName,
p.LastName,
Count(a.attendance_date) AS CountOfattendance_date,
First(a.attendance_date) AS FirstOfattendance_date,
c.total
FROM (
tblPeople AS p
INNER JOIN tblEventAttendance AS a ON
a.people_id = p.ID)
INNER JOIN (SELECT people_id, Count (attendance_date) As total
FROM (
SELECT DISTINCT people_id,attendance_date
FROM tblEventAttendance)
Group By people_id) AS c ON
p.ID = c.people_id
GROUP BY
p.ID, c.total;
Can you change
B.attendance_date >= FirstOfattendance_date
to
B.attendance_date >= First(A.attendance_date)
Related
I am having the following query and running it on postgress
select
p.id as p_id,
p.name as p_name,
p.tags,
p.creator,
p.value
p.creation_date,
cp.id as c_part_id,
fr.distance
count(*) OVER() AS total_item
from t_p p
left join t_c_part cp on p.id = cp.p_id
left join t_fl fr on p.id = fr.p_id
where p.name = 'test'
ORDER BY p.id ASC, p.name ASC
OFFSET 0 FETCH NEXT 25 ROWS only
What is missing here is that I also need to get max(p.value) and min(p.value) not affected by the "where" clause - so calculated from total (all) values.
I am dreaming that I can do it within one query and reduce the number of transactions.
Honestly not sure if it is possible!
What I tried is something like this ->
SELECT
(SELECT COUNT(*) from t_p) as count,
(SELECT json_agg(t.*) FROM (
SELECT * FROM t_p
where ***
) AS t) AS rows
But this one did not look really nice as it require additional JSON manipulation at the backend.
I discovered that I might try to use the "with" statement to create a temporary view so the where condition is only evaluated once, but did not succeed to make it works...
You can add the extra columns as scalar subqueries in the form (select min(value) from t_p). Their values are not related to the main query so they should be totally independent.
Your original query has some minor syntax issues (missing commas). I fixed those and the result is:
select
p.id as p_id,
p.name as p_name,
p.tags,
p.creator,
p.value,
p.creation_date,
cp.p_id as c_part_id,
fr.distance,
count(*) OVER() AS total_item,
(select min(value) from t_p) as min_value,
(select max(value) from t_p) as max_value
from t_p p
left join t_c_part cp on p.id = cp.p_id
left join t_fl fr on p.id = fr.p_id
where p.name = 'test'
ORDER BY p.id ASC, p.name ASC
OFFSET 0 FETCH NEXT 25 ROWS only
See running query (without any data) at DB Fiddle.
You can join to a sub-query that calculates both MIN & MAX.
...
from t_p p
left join t_c_part cp on p.id = cp.p_id
left join t_fl fr on p.id = fr.p_id
cross join (
select
min(value) as min_value
, max(value) as max_value
, avg(value) as avg_value
from t_p
) as v
...
Then use v.min_value and v.max_value in the select.
Doesn't even have to be a LATERAL.
You could get the minimum and maximum "on the side" like this:
select
p.id as p_id,
p.name as p_name,
p.tags,
p.creator,
p.value
p.creation_date,
cp.id as c_part_id,
fr.distance,
count(*) OVER() AS total_item,
p.min_value,
p.max_value
from (SELECT id,
name,
tags,
creator,
value,
creation_date,
min(value) OVER () AS min_value,
max(value) OVER () AS max_value,
FROM t_p) AS p
left join t_c_part cp on p.id = cp.p_id
left join t_fl fr on p.id = fr.p_id
where p.name = 'test'
ORDER BY p.id ASC, p.name ASC
OFFSET 0 FETCH NEXT 25 ROWS only;
Is there a way to distinct multiple columns? When I tried to do it with p.name it says that there is an error that occurred.
SELECT DISTINCT( V.NAME ),
POH.status,
poh.shipdate,
pod.orderqty,
POD.receivedqty,
POD.rejectedqty,
p.NAME
FROM purchasing.vendor v
INNER JOIN purchasing.productvendor pv
ON v.businessentityid = pv.businessentityid
INNER JOIN production.product p
ON pv.productid = P.productid
INNER JOIN purchasing.purchaseorderdetail POD
ON P.productid = POD.productid
INNER JOIN purchasing.purchaseorderheader POH
ON POD.purchaseorderid = POH.purchaseorderid
ORDER BY v.NAME,
p.NAME;
If you want one row per NAME, then you can use ROW_NUMBER():
with q as (
<your query here with columns renamed so there are no duplicates>
)
select q.*
from (select q.*,
row_number() over (partition by v_name order by v_name) as seqnum
from q
) q
where seqnum = 1;
DISTINCT is not a function, it is an operator and its scope is the entire SELECT clause
(The query formatting is just for emphasizing the point)
SELECT DISTINCT
V.NAME,
POH.status,
poh.shipdate,
pod.orderqty,
POD.receivedqty,
POD.rejectedqty,
p.NAME
FROM purchasing.vendor v
...
That answers the error you get, however, I doubt if this will give you the results you are looking for
I'm using a health database and trying to display patients who have visited the health facility more than two times. The basic query I have so far is
SELECT FirstName, LastName
FROM PATIENT
I know I have to use a subquery in there somehow, but I don't know if I need to use Count or any other operators to find patients visiting more than two times.
you could use a join with visit and count for distinct(VisitDate) filtering using having for the count > 1
SELECT FirstName, LastName , count(distinct VisitDate)
FROM PATIENT
inner join VISIT on VISIT.patientID = PATIENT.PatientID
group by FirstName, LastName
having count(distinct VisitDate) > 1
use aggregate function count and having clause for comparison
SELECT P.FirstName, P.LastName,COUNT(V.VisitID) as numberOfVisit
FROM VISIT V
JOIN PATIENT P ON P.PatientID = V.PatientID
GROUP BY V.PatientID, P.FirstName, P.LastName
HAVING COUNT(V.VisitID) > 2
By using sub query you can also get same result but no need that 1st query is more appropriate
select * from (
SELECT P.FirstName, P.LastName,COUNT(V.VisitID) as numberOfVisit
FROM VISIT V
JOIN PATIENT P ON P.PatientID = V.PatientID
GROUP BY V.PatientID, P.FirstName, P.LastName
) as T where T.numberOfVisit>2
select x.FirstName,x.LastName from (
SELECT a.FirstName, a.LastName,count(*) n
FROM PATIENTa,visit b
where a.patientid = b.patientid
group by a.FirstName, a.LastName having count(*) > 2
) x
I have following two tables:
Person {PersonId, FirstName, LastName,Age .... }
Photo {PhotoId,PersonId, Size, Path}
Obviously, PersonId in the Photo table is an FK referencing the Person table.
I want to write a query to display all the fields of a Person , along with the number of photos he/she has in the Photo table.
A row of the result will looks like
24|Ryan|Smith|28|6
How to write such query in tsql?
Thanks,
You need a subquery in order to avoid having to repeat all the columns from Person in your group by clause.
SELECT
p.PersonId,
p.FirstName,
p.LastName,
p.Age,
coalesce(ph.PhotoCount, 0) as Photocount
FROM
Person p
LEFT OUTER JOIN
(SELECT PersonId,
COUNT(PhotoId) as PhotoCount
FROM Photo
GROUP BY PersonId) ph
ON p.PersonId = ph.PersonId
SELECT
p.PersonId,
p.FirstName,
p.LastName,
p.Age,
CASE WHEN
t.ThePhotoCount IS NULL THEN 0 ELSE t.ThePhotoCount END AS TheCount
--the above line could also use COALESCE
FROM
Person p
LEFT JOIN
(SELECT
PersonId,
COUNT(*) As ThePhotoCount
FROM
Photo
GROUP BY PersonId) t
ON t.PersonId = p.PersonID
SELECT P.PersonId, FirstName, LastName,Age, COUNT(PhotoId) AS Num
FROM Person P
LEFT OUTER JOIN PHOTO PH ON P.PersonId = PH.PersonId
GROUP BY P.PersonId, FirstName, LastName,Age
select Person.*, count(PhotoId) from Person left join Photo on Person.PersonId = Photo.PersonId
IMO GROUP BY should be the solution, something like this works for me even with other table joins:
SELECT meetings.id, meetings.location, meetings.date, COUNT( users.id ) AS attendees
FROM `meetings`
LEFT JOIN users ON meetings.id = users.meeting_id
WHERE meetings.moderator_id = 'XXX'
GROUP BY meetings.id
Not sure how to ask this as I'm a bit of a database noob,
What I want to do is the following.
table tb_Company
table tb_Division
I want to return companies that have more than one division and I don't know how to do the where clause.
SELECT dbo.tb_Company.CompanyID, dbo.tb_Company.CompanyName,
dbo.tb_Division.DivisionName FROM dbo.tb_Company INNER JOIN dbo.tb_Division ON
dbo.tb_Company.CompanyID = dbo.tb_Division.DivisionCompanyID
Any help or links much appreciated.
You'll need another JOIN where you only return companies having more than one division by using a GROUP BYand a HAVINGclause.
You can read up on grouping here
Groups a selected set of rows into a
set of summary rows by the values of
one or morecolumns or expressions. One
row is returned for each group.
Aggregate functions in the SELECT
clause list provide
information about each group instead
of individual rows.
SELECT dbo.tb_Company.CompanyID
, dbo.tb_Company.CompanyName
, dbo.tb_Division.DivisionName
FROM dbo.tb_Company
INNER JOIN dbo.tb_Division ON dbo.tb_Company.CompanyID = dbo.tb_Division.DivisionCompanyID
INNER JOIN (
SELECT DivisionCompanyID
FROM dbo.tb_Division
GROUP BY
DivisionCompanyID
HAVING COUNT(*) > 1
) d ON d.DivisionCompanyID = dbo.tb_Company.CompanyID
another alternative...
SELECT c.CompanyId, c.CompanyName, d.DivisionName
FROM tbl_Company c
INNER JOIN tbl_Division d ON c.CompanyId=d.DivisionCompanyId
GROUP BY c.CompanyId, c.CompanyName, d.DivisionName
HAVING COUNT(*) > 1
How about?
WITH COUNTED AS
(
SELECT C.CompanyID, C.CompanyName, D.DivisionName,
COUNT() OVER(PARTITION BY C.CompanyID) AS Cnt
FROM dbo.tb_Company C
INNER JOIN dbo.tb_Division D ON C.CompanyID = D.DivisionCompanyID
)
SELECT *
FROM COUNTED
WHERE Cnt > 1
With the other solutions (that join onto Division table twice), a single company/division can be returned under a heavy insert load.
If a row is inserted into the Division table between the time the first join occurs and the time the second join (with the group by/having) is evaluated, the first Division join will return a single row. However, the second one will return a count of 2.
How about...
SELECT dbo.tb_Company.CompanyID,
dbo.tb_Company.CompanyName,
FROM dbo.tb_Company
WHERE (SELECT COUNT(*)
FROM dbo.tb_Division
WHERE dbo.tb_Company.CompanyID =
dbo.tb_Division.DivisionCompanyID) > 1;