I have the following query to count how many times each process_track_id occurs in a table:
SELECT
a.process_track_id,
COUNT(1) AS 'num'
FROM
transreport.process_name a
GROUP BY
a.process_track_id
This returns the following results:
process_track_id | num
1 14
2 44
3 16
5 8
6 18
7 17
8 14
This is great. Now is the part where I am stuck. I would like to get the following table:
num count
8 1
14 2
16 1
17 1
18 1
44 1
Where num are the distinct counts from the first table, and count is how many times that frequency occurs.
Here is what I have tried (it's a subquery, but I'm not sold on the method) and I haven't been able to get it to work just yet. I'm new to SQL and I think I'm missing out on some some key aspects of the syntax.
SELECT
X.id_count,
count(1) as 'num_count'
FROM
(SELECT
a.process_track_id,
COUNT(1) AS 'id_count'
FROM
transreport.process_name a
GROUP BY
a.process_track_id
--COUNT(1) AS 'id_count'
) X;
Any ideas?
It's probably good to keep in mind that this may have to be run on a database with at least 1 million records, and I don't have the ability to create a new table in the process.
Thanks!
Here's the subquery method you were driving at:
SELECT id_count, COUNT(*) AS 'num_count'
FROM (SELECT a.process_track_id
,COUNT(*) AS 'id_count'
FROM transreport.process_name a
GROUP BY a.process_track_id
)sub
GROUP BY id_count
Not sure there's a better method as the aggregation needs to run once anyway.
Try this
SELECT x.num, COUNT(*) AS COUNT
FROM (
SELECT
a.process_track_id, -- <--- You may removed this column
COUNT(*) AS 'num'
FROM
transreport.process_name a
GROUP BY
a.process_track_id
) X
GROUP BY X.num
Related
My goal is something like following table:
Key | Count since date X | Count total
1 | 4 | 28
With two simple selects I could gain this values: (the key of the table consists of 3 columns [t$ncmp, t$trav, t$seqn])
1. SELECT COUNT(*) FROM db.table WHERE t$date >= sysdate-2 GROUP BY t$ncmp, t$trav, t$seqn
2. SELECT COUNT(*) FROM db.table GROUP BY t$ncmp, t$trav, t$seqn
How can I join these statements?
What I tried:
SELECT n.t$trav, COUNT(n.t$trav), m.total FROM db.table n
LEFT JOIN (SELECT t$ncmp, t$trav, t$seqn, COUNT(*) as total FROM db.table
GROUP BY t$ncmp, t$trav, t$seqn) m
ON (n.t$ncmp = m.t$ncmp AND n.t$trav = m.t$trav AND n.t$seqn = m.t$seqn)
WHERE n.t$date >= sysdate-2
GROUP BY n.t$ncmp, n.t$trav, n.t$seqn
I tried different variantes, but always got errors like 'group by is missing' or 'unknown qualifier'.
Now this at least executes, but total is always 2.
T$TRAV COUNT(N.T$TRAV) TOTAL
4 2 2
29 3 2
51 1 2
62 2 2
16 1 2
....
If it matter, I will run this as an OPENQUERY from MSSQLSERVER to Oracle-DB.
I'd try
GROUP BY n.t$trav, m.total
You typically GROUP BY the same columns as you SELECT - except those who are arguments to set functions.
My goal is something like following table:
If so, you seem to want conditional aggregation:
select key, count(*) as total,
sum(case when datecol >= date 'xxxx-xx-xx' then 1 else 0 end) as total_since_x
from t
group by key;
I'm not sure how this relates to your sample queries. I simply don't see the relationship between that code and your question.
Imagine I have a table like this:
# | A | B | MoreFieldsHere
1 1 1
2 1 3
3 1 5
4 2 6
5 2 7
6 3 9
B is associated to A in an 1:n relationship. The table could've been created with a join for example.
I want to get both the total count and the count of different A.
I know I can use a query like this:
SELECT v1.cnt AS total, v2.cnt AS num_of_A
FROM
(
SELECT COUNT(*) AS cnt
FROM SomeComplicatedQuery
WHERE 1=1
-- AND SomeComplicatedCondition
) v1,
(
SELECT COUNT(A) AS cnt
FROM SomeComplicatedQuery
WHERE 1=1
-- AND SomeComplicatedCondition
GROUP BY A
) v2
However SomeComplicatedQuery would be a complicated and slow query and SomeComplicatedCondition would be the same in both cases. And I want to avoid calling it unnessesarily. Aside from that if the query changes, you need to make sure to change it in the other place too, making it prone to error and creating (probably unnessesary) work.
Is there a way to do this more efficiently?
Are you looking for this?
SELECT COUNT(*) AS total, COUNT(DISTINCT A) AS num_of_A
FROM (. . . ) q
This question already has answers here:
Retrieving last record in each group from database - SQL Server 2005/2008
(2 answers)
Closed 7 years ago.
This has probably been asked before, but I have no idea on how to find it in the first place.
In the following query (with respective returned values):
select * from tbChapter where idLesson in(12, 13)
-- Result --
id idLesson name sequence
52 12 Intro 1
53 12 Chapter One 2
54 12 Chapter Two 3
55 13 Intro 1
56 13 Chapter One 2
57 13 Chapter Two 3
58 13 Chapter Three 4
I want to get only the last entry for each idLesson, for example:
-- Expected result --
id idLesson name sequence
54 12 Chapter Two 3
58 13 Chapter Three 4
How can I proceed?
Ps: I'l actually replace where idLesson in(12, 13) with subquery that will return dozens of idLesson values.
Try this:
select * from tbChapter where id in
(select MAX(id) from tbChapter group by idLesson)
Try this:
select *
from tbChapter as a
where sequence = (select max(sequence)
from tbChapter as b
where a.id_lesson = b.id_lesson)
The canonical way is to use window functions. Here is an example:
select c.*
from (select c.*, max(sequence) over (partition by idLesson) as maxs
from tblChapter c
) c
where sequence = maxs;
A more creative way that might perform better under some circumstances is to use cross apply:
select c.*
from (select distinct idLesson from tblChapter) l cross apply
(select top 1 c*
from tblChapter c
where c.idLesson = l.idLesson
order by sequence desc
) c;
Note that the first subquery can be replaced by a table that has all the lessons, with one per row.
SELECT
Max(id),
idlesson,
name,
Max(sequence)
FROM
tbChapter
WHERE
idLesson in(12, 13)
GROUP BY
idlesson,
name
I have a simple question regarding oracle sql. So i have this table
WEEKNUM DATA
1 10
2 4
3 6
4 7
So i want to make a view that shows like this,
WEEKNUM DATA ACCUM_DATE
1 10 10
2 4 14
3 6 20
4 7 27
I spend hours on this simple one but couldnt get any luck
thanks a lot
SELECT weeknum,
data,
sum(data) over (order by weeknum) accum_data
FROM your_table_name
should work. I'm using the sum analytic function here and assuming that you want to start with the smallest weeknum value and keep increasing the running total as the weeknum values increase. I'm also assuming that you never want to reset the accumulated sum. If you're trying to do something like generating an accumulated sum that restarts each year, you'd want to add a partition by to the analytic function.
You could use a Cross JOin in this case
Query:
select
A.WEEKNUM
, A.DATA
, SUM(B.DATA) DA
from table1 A
cross join table1 B
WHERE A.WEEKNUM>=B.WeekNUM
GROUP BY A.WEEKNUM
, A.DATA
order by A.WEEKNUM
Result:
WEEKNUM DATA DA
1 10 10
2 4 14
3 6 20
4 7 27
Thanks guys but i just found out this method works perfectly,
OVER (ORDER BY WEEKNUM ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS CUMULATIVE_WEIGHT
Or use a sub-select to calculate:
select WEEKNUM, DATA, (select sum(DATA) from tablename t2
where t2.weeknum <= t1.weeknum) as ACCUM_DATE
from tablename t1
I have a sql / sqlite question. I need to write a query that select some values from a sqlite database table. I always want the maximal returned records to be 20. If the total selected records are more than 20 I need to select 20 records that are spread evenly (no random) over the total records. It is also important that I always select the first and last value from the table when sorted on the date. These records should be inserted first and last in the result.
I know how to accomplish this in code but it would be perfect to have a sqlite query that can do the same.
The query Im using now is really simple and looks like this:
"SELECT value,date,valueid FROM tblvalue WHERE tblvalue.deleted=0 ORDER BY DATE(date)"
If I for example have these records in the talbe and to make an easier example the maximum result I want is 5.
id value date
1 10 2010-04-10
2 8 2010-04-11
3 8 2010-04-13
4 9 2010-04-15
5 10 2010-04-16
6 9 2010-04-17
7 8 2010-04-18
8 11 2010-04-19
9 9 2010-04-20
10 10 2010-04-24
The result I would like is spread evenly like this:
id value date
1 10 2010-04-10
3 8 2010-04-13
5 10 2010-04-16
7 8 2010-04-18
10 10 2010-04-24
Hope that explain what I want, thanks!
Something like this should work for you:
SELECT *
FROM (
SELECT v.value, v.date, v.valueid
FROM tblvalue v
LEFT OUTER JOIN (
SELECT min(DATE(date)) as MinDate, max(DATE(date)) as MaxDate
FROM tblvalue
WHERE tblvalue.deleted = 0
) vm on DATE(v.date) = vm.MinDate or DATE(v.date) = vm.MaxDate
WHERE tblvalue.deleted = 0
ORDER BY vm.MinDate desc, Random()
LIMIT 20
) a
ORDER BY DATE(date)
I think you want this:
SELECT value,date,valueid FROM tblvalue WHERE tblvalue.deleted=0
ORDER BY DATE(date), Random()
LIMIT 20
In other words you want select rows with date column, so that date is from the sorted list of dates, from where we take every odd element? And add the last recorded element (with the latest date)? And everything limited to max 20 rows?
If that's the case, then I think this one should do:
SELECT id,value,date FROM source_table WHERE date IN (SELECT date FROM source_table WHERE (rowid-1) % 2 = 0 OR date = (SELECT max(date) FROM source_table) ORDER BY date) LIMIT 20