I have a table called Customer:
|device_id|user_id|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 2 |
| 7 | 3 |
Now I want to return only the entries which have only 1 device per user. In this case only
|device_id|user_id|
| 7 | 3 |
Should be returned because user_id 3 is the only one with only 1 device (user_id 1 has 4, user_id 2 has 2)
How would I do that with a query?
One method is not exists:
select t.*
from t
where not exists (select 1
from t t2
where t2.user_id = t.user_id and t2.device_id <> t.device_id
);
You can also use aggregation:
select device_id, max(user_id) as user_id
from t
group by device_id
having count(*) = 1;
We can use group by to group the data on the basis of user_id followed by aggregate funciton to get the count of device:
SELECT device_id,user_id FROM customer where user_id IN
(
SELECT user_id from
(
SELECT user_id,count(*) FROM customer GROUP BY user_id HAVING count(*)<2
)
);
Related
I have a table:
| id | Number |Address
| -----| ------------|-----------
| 1 | 0 | NULL
| 1 | 1 | NULL
| 1 | 2 | 50
| 1 | 3 | NULL
| 2 | 0 | 10
| 3 | 1 | 30
| 3 | 2 | 20
| 3 | 3 | 20
| 4 | 0 | 75
| 4 | 1 | 22
| 4 | 2 | 30
| 5 | 0 | NULL
I need to get: the NUMBER of the last ADDRESS change for each ID.
I wrote this select:
select dh.id, dh.number from table dh where dh =
(select max(min(t.history)) from table t where t.id = dh.id group by t.address)
But this select not correctly handling the case when the address first changed, and then changed to the previous value. For example id=1: group by return:
| Number |
| -------- |
| NULL |
| 50 |
I have been thinking about this select for several days, and I will be happy to receive any help.
You can do this using row_number() -- twice:
select t.id, min(number)
from (select t.*,
row_number() over (partition by id order by number desc) as seqnum1,
row_number() over (partition by id, address order by number desc) as seqnum2
from t
) t
where seqnum1 = seqnum2
group by id;
What this does is enumerate the rows by number in descending order:
Once per id.
Once per id and address.
These values are the same only when the value is 1, which is the most recent address in the data. Then aggregation pulls back the earliest row in this group.
I answered my question myself, if anyone needs it, my solution:
select * from table dh1 where dh1.number = (
select max(x.number)
from (
select
dh2.id, dh2.number, dh2.address, lag(dh2.address) over(order by dh2.number asc) as prev
from table dh2 where dh1.id=dh2.id
) x
where NVL(x.address, 0) <> NVL(x.prev, 0)
);
I have two tables of events in bigquery that look like as follows. The main idea is two count the number of events in each table (are always pairs of event_id and user_id) and join them in a single table that for each pair in any table it tells the number of events.
table 1:
| event_id | user id |
| -------- | ------- |
| 1 | 1 |
| 2 | 1 |
| 2 | 3 |
| 2 | 5 |
| 1 | 1 |
| 4 | 7 |
table 2:
| event_id | user id |
| -------- | ------- |
| 1 | 1 |
| 3 | 1 |
| 2 | 3 |
I would like to get a table which has the number of events of each table:
| event_id | user id | num_events_table1 | num_events_table2 |
| -------- | ------- | ----------------- | ----------------- |
| 1 | 1 | 2 | 1 |
| 2 | 1 | 1 | 0 |
| 2 | 3 | 1 | 1 |
| 2 | 5 | 1 | 0 |
| 4 | 7 | 1 | 0 |
| 3 | 1 | 0 | 1 |
Any idea of how to do this with sql? I have tried this:
SELECT i1, e1, num_viewed, num_displayed FROM
(SELECT id as i1, event as e1, count(*) as num_viewed
FROM table_1
group by id, event) a
full outer JOIN (SELECT id as i2, event as e2, count(*) as num_displayed
FROM table_2
group by id, event) b
on a.i1 = b.i2 and a.e1 = b.e2
This is not getting exactly what I want. I amb getting i1 which are null and e1 that are null.
Consider below
#standardSQL
with `project.dataset.table1` as (
select 1 event_id, 1 user_id union all
select 2, 1 union all
select 2, 3 union all
select 2, 5 union all
select 1, 1 union all
select 4, 7
), `project.dataset.table2` as (
select 1 event_id, 1 user_id union all
select 3, 1 union all
select 2, 3
)
select event_id, user_id,
countif(source = 1) as num_events_table1,
countif(source = 2) as num_events_table2
from (
select 1 source, * from `project.dataset.table1`
union all
select 2, * from `project.dataset.table2`
)
group by event_id, user_id
if applied to sample data in your question - output is
If I understand correctly, the simplest method is to modify your query via a USING clause along with COALESCE():
SELECT id, event, COALESCE(num_viewed, 0), COALESCE(num_displayed, 0)
FROM (SELECT id, event, count(*) as num_viewed
FROM table_1
GROUP BY id, event
) t1 FULL JOIN
(SELECT id , event, COUNT(*) as num_displayed
FROM table_2
GROUP BY id, event
) t2
USING (id, event);
Note: This requires that the two columns used for the JOIN have the same name. If this is not the case, then you might still need column aliases in the subqueries.
One way is aggregate the union
select event_id, user id, sum(cnt1) cnt1, sum(cnt2) cnt2
from (
select event_id, user id, 1 cnt1, 0 cnt2
from table_1
union all
select event_id, user id, 0 cnt1, 1 cnt2
from table_2 ) t
group by event_id, user id
I have two table
Let's name as first table: QC_Meeting_Master
Second table: QC_Project_Master I want to calculate count of problems_ID Which is mutually depend on second table
ID | QC_ID | Problems_ID |
___|_______|_____________|
1 | 1 | 2 |
2 | 1 | 7 |
ID | QC_ID | Problem_ID |
___|_______|_____________|
1 | 1 | 7 |
2 | 1 | 7 |
3 | 1 | 7 |
4 | 1 | 7 |
5 | 1 | 2 |
6 | 1 | 2 |
7 | 1 | 2 |
select COUNT(Problem_ID) from [QC_Project_Master] where Problem_ID in
(select Problems_ID from QC_Meeting_Master QMM join QC_Project_Master QPM on QMM.Problems_ID = QPM.Problem_ID)
I have to calculate Count of QC_Project_Master (problem_ID) on basis of QC_Meeting_Master (Problems_ID)
it means for first table: QC_Meeting_Master(Problems_ID) = 2,
then count should be 3
And for Second table: QC_Project_Master (Problems_ID) = 7,
then count should be 4
use conditional aggregation
select sum(case when t2.Problem_ID=2 then 1 else 0 end),
sum(case when t2.Problem_ID=7 then 1 else 0 end) from
table1 t1 join table2 t2 on t1.QC_ID=t2.QC_ID and t1.Problems_ID=t2.Problems_ID
if you need all the group count then use below
select t2.QC_ID,t2.Problems_ID, count(*) from
table1 t1 join table2 t2
on t1.QC_ID=t2.QC_ID and t1.Problems_ID=t2.Problems_ID
group by t2.QC_ID,t2.Problems_ID
As far as I understood your problem this is simple aggregation and JOIN as below:
SELECT mm.QC_ID, mm.Problem_ID, pm.cnt
FROM QC_Meeting_Master mm
INNER JOIN
(
SELECT QC_ID, Problem_ID, COUNT(*) cnt
FROM QC_Project_Master
GROUP BY QC_ID, Problem_ID
) pm
ON pm.QC_ID = mm.QC_ID AND pm.Problem_ID = mm.Problem_ID;
I have table friends below.
-----------------------------
| id | user_id | friends_id |
-----------------------------
| 1 | 1 | 2 |
-----------------------------
| 2 | 1 | 3 |
-----------------------------
| 3 | 1 | 4 |
-----------------------------
| 4 | 2 | 1 |
-----------------------------
| 5 | 3 | 5 |
-----------------------------
| 6 | 4 | 5 |
-----------------------------
and SQL query:
select user_id, friends_id from friends where user_id = 1
Above query gives me below result.
------------------------
| user_id | friends_id |
------------------------
| 1 | 2 |
------------------------
| 1 | 3 |
------------------------
| 1 | 4 |
------------------------
I want to get resul like this:
------------------------
| user_id | friends_id |
------------------------
| 1 | many |
------------------------
If any user have friends more than 1, i must write word 'many'.
If any user have 1 friend, i must write his ID.
How i can do that?
I googled and can't explain to google my problem.
Do a GROUP BY to count number of friends. Use a CASE to return 'Many' if more than 1 friend, or the friend_id if only one (need to CAST to a character type, compatible with 'Many'.)
select user_id,
case when count(friends_id) > 1 then 'Many'
else cast(min(friends_id) as varchar(11)) end as friends_id
from friends
group by user_id
I update the query and include
SQL FIDDLE DEMO
WITH fCount as (
SELECT user_id, min(friends_id) friends_id, count(friends_id) nFriend
FROM friends
GROUP BY user_id
)
select user_id, CASE
WHEN nFriend > 1 THEN 'many'
ELSE cast(friends_id as nvarchar(10))
END friends_id
from fCount
try this
select user_id, CASE
WHEN count(friends_id) > 1 THEN 'many'
ELSE friends_id
END friends_id
from friends
where user_id = 1
Hi you can use below query:
CREATE TABLE #Temp (
ID INT Identity(1, 1)
,UID INT
,f_id NVARCHAR(10)
)
INSERT INTO #temp
SELECT 1
,2
UNION ALL
SELECT 1
,3
UNION ALL
SELECT 1
,4
UNION ALL
SELECT 2
,1
SELECT uid
,COUNT(f_id) AS COUNT_of_Friends
INTO #Temp2
FROM #temp
GROUP BY Uid
SELECT t1.Uid
,CASE
WHEN t2.COUNT_of_Friends > 1
THEN 'Many'
ELSE f_id
END AS F_id
FROM #temp T1
INNER JOIN #Temp2 T2 ON T1.Uid = t2.Uid
I got those two tables sport and student:
First table sport:
|idsport | name |
_______________________
| 1 | bobsled |
| 2 | skating |
| 3 | boarding |
| 4 | iceskating |
| 5 | skiing |
Second table student:
foreign key
|idstudent | name | sport_idsport
__________________________________________
| 1 | john | 3 |
| 2 | pauly | 2 |
| 3 | max | 1 |
| 4 | jane | 2 |
| 5 | nico | 5 |
so far i did this it output which number is mostly inserted, but cant get it to work
with two tables
SELECT sport_idsport
FROM (SELECT sport_idsport FROM student GROUP BY sport_idsport ORDER BY COUNT(*) desc)
WHERE ROWNUM<=1;
I need to output name of most popular sport, in that case it would be skating.
I use oracle sql.
with counter as (
Select sport_idsport,
count(*) as cnt,
dense_rank() over (order by count(*) desc) as rn
from student
group by sport_idsport
)
select s.*, c.cnt
from sport s
join counter c on c.sport_idsport = s.idsport and c.rn = 1;
SQLFiddle example: http://sqlfiddle.com/#!4/b76e21/1
select cnt, sport_idsport from (
select count(*) cnt, sport_idsport
from student
group by sport_idsport
order by count(*) desc
)
where rownum = 1