I want to have a switch case in my SQL query such that when the group by does not group any element i dont want to aggregate otherwise I want to. Is that possible.
my query is something like this:
select count(1),AVG(student_mark) ,case when Count(1)=1 then student_subjectid else null end from Students
group by student_id
i get this error Column 'student_subjectid' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.
Thanks in advance..
SELECT
student_id,
COUNT(*) AS MarkCount,
AVG(student_mark) AS student_mark,
CASE COUNT(*) WHEN 1 THEN MIN(student_subjectid) END AS student_subjectid
FROM Students
GROUP BY student_id
Why in the world would you complicate it?
select count(1), AVG(Student_mark) Student_mark
from Students
group by student_id
If there is only one student_mark, it is also the SUM, AVG, MIN and MAX - so just continue to use the aggregate!
EDIT
The dataset that would eventuate with your requirement will not normally make sense. The way to achieve that would be to merge (union) two different results
select
numRecords,
Student_mark,
case when numRecords = 1 then student_subjectid end # else is implicitly NULL
from
(
select
count(1) AS numRecords,
AVG(Student_mark) Student_mark,
min(student_subjectid) as student_subjectid
from Students
group by student_id
) x
Related
I attempted the 1407. Top Travellers. But am struggling with my Oracle query below, 'Runtime error'. A little too tired to understand why. Any idea where I am going wrong? Have been rusty with SQL of late. :(
select name as name,
case when rides.distance is null then 0 else sum(rides.distance) end as travelled_distance
from users
left join rides
on users.id = rides.user_id
group by rides.users_id
order by travelled_distance desc, name;
As commented, is another way round:
select
name,
sum(case when rides.distance is null then 0 else rides.distance end) as travelled_distance
from users left join rides on users.id = rides.user_id
group by name
order by travelled_distance desc, name;
Or, simpler, use the nvl function:
select
name,
sum(nvl(rides.distance, 0)) as travelled_distance
from ...
Though, a few more objections:
you should use table aliases (as they simplify query and improve readability)
moreover, you should precede all column names with table aliases; in your case, you failed to do so for the name column. It probably belongs to the users table, but we can't tell for sure as we don't have your data model nor access to your database
group by clause should contain column(s) that aren't aggregated. In your query, that's the name column. You can put rides.users_id into that clause, but you must put name in there
The below solution works. Thanks to one of the Discussion posts at leetcode I could figure out the issue:
select r.name,
case when x.td is null
then 0
else x.td
end travelled_distance
from Users r
left join
(
select user_id, sum(distance) td
from Rides
group by user_id
) x
on r.id = x.user_id
order by travelled_distance desc, r.name;
I am pretty much stuck with a problem I am facing with SQL Server. I want to show in a query the amount of times that specific value occurs. This is pretty easy to do, but I want to take it a step further and I think the best way to explain on what I am trying to achieve is to explain it using images.
I have two tables:
Plant and
Chest
As you can see with the chest the column 'hoeveelheid' tells how full the chest is, 'vol' == 1 and 3/4 is == 0,75. In the plant table there is a column 'Hoeveelheidperkist' which tells how much plants there can be in 1 chest.
select DISTINCT kist.Plantnaam, kist.Plantmaat, count(*) AS 'Amount'
from kist
group by kist.plantnaam, kist.Plantmaat
This query counts all the chests, but it does not seperate the count of 'Vol' chests and '3/4' chests. It only does This. What I want to achieve is this. But I have no idea how. Any help would be much appreciated.
If you use group by you don't need distinct
and if you want the seprated count for hoeveelheid you ust add to the group by clause
select DISTINCT kist.Plantnaam, kist.Plantmaat, kist.hoeveelheid, count(*) AS 'Amount'
from kist
group by kist.plantnaam, kist.Plantmaat, hoeveelheid
or if you want all the 3 count ond the samw rowx you could use a condition aggreagtion eg:
select DISTINCT kist.Plantnaam, kist.Plantmaat
, sum(case when kist.hoeveelheid ='Vol' then 1 else 0 end) vol
, sum(case when kist.hoeveelheid ='3/3' then 1 else 0 end) 3_4
, count(*) AS 'Amount'
from kist
group by kist.plantnaam, kist.Plantmaat
When you want to filter the data on the counts you have to use having clause. When ever you are using aggregate functions(sum, count, min, max) and you want to filter them on aggregation basis, use having clause
select DISTINCT kist.Plantnaam, kist.Plantmaat, count(*) AS 'Amount'
from kist
group by kist.plantnaam, kist.Plantmaat having count(*) = 1 -- or provide necessary conditions
I have a table called Test. It has three columns Fn(varchar),Un(number),INS(date). What I am trying to do is select all rowsfrom the table and get the sum of common values in column Fn.
Example
Fn Un INS
---------------
1 6 9-Jan-2017
2 8 9-Jan-2017
1 5 4-Jan-2017`
I am trying to sum common values based on Fn column so the result would be
Fn Un
1 11
I am trying to understand how to CASE IF ELSE in Oracle. But not able to add them because the INS date is different for both of them. Is there any way to achieve this. Thanks.
I think you need group by like below:
select fn, sum(un) as total
from t
group by fn
order by total desc;
You can use Aggregate functions(Average, Sum, Max, Min..) in sql with group by.
https://en.wikipedia.org/wiki/Aggregate_function
You seem to want group by:
select fn, sum(un)
from t
group by fn
having count(*) >= 2;
Try LISTAGG function for INS column
SELECT Fn, SUM(Un) as Total, LISTAGG(INS, '; ') WITHIN GROUP (ORDER BY Fn) as INSs
FROM T
GROUP BY Fn
ORDER BY Total DESC;
I have searched a lot, but most of solutions are for concatenation option and not what I really want.
I have a table called X (in a Postgres database):
anm_id anm_category anm_sales
1 a_dog 100
2 b_dog 50
3 c_dog 60
4 a_cat 70
5 b_cat 80
6 c_cat 40
I want to get total sales by grouping 'a_dog', 'b_dog', 'c_dog' as dogs and 'a_cat', 'b_cat', 'c_cat' as cats.
I cannot change the data in the table as it is an external data base from which I am supposed to get information only.
How to do this using an SQL query? It does not need to be specific to Postgres.
Use case statement to group the animals of same categories together
SELECT CASE
WHEN anm_category LIKE '%dog' THEN 'Dogs'
WHEN anm_category LIKE '%cat' THEN 'cats'
ELSE 'Others'
END AS Animals_category,
Sum(anm_sales) AS total_sales
FROM yourtables
GROUP BY CASE
WHEN anm_category LIKE '%dog' THEN 'Dogs'
WHEN anm_category LIKE '%cat' THEN 'cats'
ELSE 'Others'
END
Also this query should work with most of the databases.
By using PostgreSQL's split_part()
select animal||'s' animal_cat,count(*) total_sales,sum(anm_sales) sales_sum from(
select split_part(anm_cat,'_',2) animal,anm_sales from x
)t
group by animal
sqlfiddle
By creating split_str() in MySQL
select animal||'s' animal_cat,count(*) total_sales,sum(anm_sales) sales_sum from(
select split_str(anm_cat,'_',2) animal,anm_sales from x
)t
group by animal
sqlfiddle
You could group by a substr of anm_catogery:
SELECT SUBSTR(anm_catogery, 3) || 's', COUNT(*)
FROM x
GROUP BY anm_catogery
If you have a constant length of the appendix like in the example:
SELECT CASE right(anm_category, 3) AS animal_type -- 3 last char
, sum(anm_sales) AS total_sales
FROM x
GROUP BY 1;
You don't need a CASE statement at all, but if you use one, make it a "simple" CASE:
Simplify nested case when statement
Use a positional reference instead of repeating a possibly lengthy expression.
If the length varies, but there is always a single underscore like in the example:
SELECT split_part(anm_category, '_', 2) AS animal_type -- word after "_"
, sum(anm_sales) AS total_sales
FROM x
GROUP BY 1;
When I run the script below, I got a error message "Cannot perform an aggregate function on an expression containing an aggregate or a subquery" Please provide some advice. Thanks
SELECT
CONVERT(DECIMAL(18,5),SUM(CASE WHEN PATIENT_ACCOUNT_NO IN (
SELECT PATIENT_ACCOUNT_NO
FROM STND_ENCOUNTER
GROUP BY PATIENT_ACCOUNT_NO
HAVING ( COUNT(PATIENT_ACCOUNT_NO) > 1)) THEN 0 ELSE 1 END)) dupPatNo
FROM [DBO].[STND_ENCOUNTER]
I think the error message is pretty clear. You have a sum() function with a subquery in it (albeit within a case, but that doesn't matter).
It seems that you want to choose patients that have more than one encounter, then add 0 if the patients is in the list and 1 if the patient is not. Hmmm. . . sounds like you want to count the number of patients with only one encounter.
Try using this logic instead:
select count(*)
from (select se.*, count(*) over (partition by PATIENT_ACCOUNT_NO) as NumEncounters
from dbo.stnd_encounter se
) se
where NumEncounters = 1;
As a note, the variable you are assigning is called DupPatientNo. This sounds like the number of patients that have duplicates. In that case, the query is:
select count(distinct PATIENT_ACCOUNT_NO)
from (select se.*, count(*) over (partition by PATIENT_ACCOUNT_NO) as NumEncounters
from dbo.stnd_encounter se
) se
where NumEncounters > 1;
(Or use count(*) if you want the number of encounters on duplicate patients.)
If you want to find number of PATIENT_ACCOUNT_NO that does not have any duplicates then use the following
SELECT COUNT(DISTINCT dupPatNo.PATIENT_ACCOUNT_NO)
FROM (
SELECT PATIENT_ACCOUNT_NO
FROM STND_ENCOUNTER
GROUP BY PATIENT_ACCOUNT_NO
HAVING COUNT(PATIENT_ACCOUNT_NO) = 1
) dupPatNo
If you want to find number of PATIENT_ACCOUNT_NO that have atleast one duplicate then use the following
SELECT COUNT(DISTINCT dupPatNo.PATIENT_ACCOUNT_NO)
FROM (
SELECT PATIENT_ACCOUNT_NO
FROM STND_ENCOUNTER
GROUP BY PATIENT_ACCOUNT_NO
HAVING COUNT(PATIENT_ACCOUNT_NO) > 1
) dupPatNo
Use of DISTINCT will make the query not count same item again and again
Though your query looks for first result, its not clear what you want. Hence giving query for both