I'm looking for a way of choosing the most recent item (date) from the set in Hive. For instance a have the following table t1:
item date
a 2016-01-01
a 2016-02-04
b 2016-01-10
after
hive> select item, collect_set(date) as dates from t1 group by item;
i have
item dates
a [2016-01-01, 2016-02-04]
b [2016-01-10]
So now I need to get rid of absolete dates, i.e., create table like
item date
a 2016-02-04
b 2016-01-10
Can anyone help?
Just use max():
select item, max(date) as date
from t1
group by item;
If you actually want a new table, you can use create table as.
Related
I have the following table in DolphinDB:
n=1000000
t1=table(rand(`a`b`c,n)as ID, rand(2017.08.16..2018.09.15,n) as date ,rand(10.0,n) as price)
What I am trying to do is transpose the table into a panel data that all dates are in one column, for example:
date a b c
2017.08.16 1.1246 4.6269 2.3019
2017.08.17 7.8525 9.7178 2.916741
...
Is there an efficient way to do it in DolphinDB？
You can try this:
panel(t1.date,t1.ID,t1.price, 2017.08.16..2018.09.15)
another way:
select price from t1 pivot by date,ID
I have a multiple rows data with unique start date and end date combination.
I want to replace the start date with the minimum of all the start dates
and End date with maximum of all the end dates.
Example:
id start Date end Date
1005 09/01/2000 05/31/2001
1005 09/05/2000 05/23/2001
100775 03/15/2005 04/30/2005
100775 03/25/2005 04/22/2005
3273 09/01/2003 12/31/2004
3273 09/11/2003 12/11/2004
Now I want the output to look like:
id start Date end date
1005 09/01/2000 05/31/2001
1005 09/01/2000 05/31/2001
100775 03/15/2005 04/30/2005
100775 03/15/2005 04/30/2005
3273 09/01/2003 12/31/2004
3273 09/01/2003 12/31/2004
I have tried doing this with max and min functions but that doesn't work since I want this to be only one query for using it in oracle report builder.
You can use just use min and max function to get your desired output:
select
id,
min(start_date) OVER (PARTITION BY id) start_date,
max(end_date) OVER (PARTITION BY id) end_date
FROM table1;
SQL Fiddle Demo
Another way of doing this,
UPDATE T1 SET StartDate = MinStartDate, EndDate = MaxEndDate
FROM (
Select id, min(StartDate) as 'MinStartDate',
Max(EndDate) as 'MaxEndDate'
from T1
Group by id
) AS T2
WHERE T1.id = T2.id;
I got one Source table with a timestamp column (YYYY.MM.DD HH24:MI:SS) and a target table with aggregated rows on daily basis (Date column: YYYY.MM.DD).
My Problem is: How do I bring new data from source to target and aggregate it?
I tried:
select
a.Sales,
trunc(a.timestamp,'DD') as TIMESTAMP,
count(1) as COUNT,
from
tbl_Source a
where trunc(a.timestamp,'DD') > nvl((select MAX(b.TIME_TO_DAY)from tbl_target b), to_date('01.01.1975 00:00:00','dd.mm.yyyy hh24:mi:ss'))
group by a.sales,
trunc(a.Timestamp,'DD')
The problem with that is: when I have a row with timestamp '2013.11.15 00:01:32' and the max day from target is the 14th of november, it will only aggregate the 15th. Would I use >= instead of > some rows would get loaded twice.
It looks like you are looking for a merge statement: If the day is already present in tbl_target then update the count else insert the record.
merge into tbl_target dest
using
(
select sales, trunc(timestamp) as theday , count(*) as sales_count
from tbl_Source
where trunc(timestamp) >= ( select nvl(max(time_to_day),to_date('01.01.1975','dd.mm.yyyy')) from tbl_target )
group by sales, trunc(timestamp)
) src
on (src.theday = dest.time_to_day)
when matched then update set
dest.sales_count = src.sales_count
when not matched then
insert (time_to_day, sales_count)
values (src.theday, src.sales_count)
;
As far as I can understand your question: you need to get everything since the last reload to target table.
The problem here: you need this date, but it is truncated during the update.
If my guesses are correct you cannot do anything except to store the date of reload as an additional column because there is no way to get it back from the data presented here.
about your query:
count(*) and count(1) are the same in performance (proved many times, at least in 10-11 versions) - do not make this count(1), looks really ugly
do not use nvl, use coalesce instead of it - it is much faster
I would write your query like that:
with t as (select max(b.time_to_day) mx from tbl_target b)
select a.sales,trunc(a.timestamp,'dd') as timestamp,count(*) as count
from tbl_source a,t
where trunc(a.timestamp,'dd') > t.mx or t.mx is null
group by a.sales,trunc(a.timestamp,'dd')
Does this fit your needs:
WHERE trunc(a.timestamp,'DD') > nvl((select MAX(b.TIME_TO_DAY) + 1 - 1/(24*60*60) from tbl_target b), to_date('01.01.1975 00:00:00','dd.mm.yyyy hh24:mi:ss'))
i.e. instead of 2013-11-15 00:00:00 compare to 2013-11-16 23:59:59
Update:
This one?
WHERE trunc(a.timestamp,'DD') BETWEEN nvl((select MAX(b.TIME_TO_DAY) from ...) AND nvl((select MAX(b.TIME_TO_DAY) + 1 - 1/(24*60*60) from ...)
I have dates in this format in my database "01-APR-12" and the column is a DATE type.
My SQL statement looks like this:
SELECT DISTINCT c.customerno, c.lname, c.fname
FROM customer c, sales s
WHERE c.customerno = s.customerno AND s.salestype = 1
AND (s.salesdate BETWEEN '01-APR-12' AND '31-APR-12');
When I try to do it that way, I get this error -- ORA-01839: date not valid for month specified.
Can I even use the BETWEEN keyword with how the date is setup in the database?
If not, is there another way I can get the output of data that is in that date range without having to fix the data in the database?
Thanks!
April has 30 days not 31.
Change
SELECT DISTINCT c.customerno, c.lname, c.fname
FROM customer c, sales s
WHERE c.customerno = s.customerno AND s.salestype = 1
AND (s.salesdate BETWEEN '01-APR-12' AND '31-APR-12');
to
SELECT DISTINCT c.customerno, c.lname, c.fname
FROM customer c, sales s
WHERE c.customerno = s.customerno AND s.salestype = 1
AND (s.salesdate BETWEEN '01-APR-12' AND '30-APR-12');
and you should be good to go.
In case the dates you are checking for range from 1st day of a month to the last day of a month then you may modify the query to avoid the case where you have to explicitly check the LAST day of the month
SELECT DISTINCT c.customerno, c.lname, c.fname
FROM customer c, sales s
WHERE c.customerno = s.customerno
AND s.salestype = 1 AND (s.salesdate BETWEEN '01-APR-12' AND LAST_DAY(TO_DATE('APR-12', 'MON-YY'));
The LAST_DAY function will provide the last day of the month.
The other answers are missing out on something important and will not return the correct results. Dates have date and time components. If your salesdate column is in fact a date that includes time, you will miss out on any sales that happened on April 30 unless they occurred exactly at midnight.
Here's an example:
create table date_temp (temp date);
insert into date_temp values(to_date('01-APR-2014 15:12:00', 'DD-MON-YYYY HH24:MI:SS'));
insert into date_temp values(to_date('30-APR-2014 15:12:00', 'DD-MON-YYYY HH24:MI:SS'));
table DATE_TEMP created.
1 rows inserted.
1 rows inserted.
select * from date_temp where temp between '01-APR-2014' and '30-APR-2014';
Query Result: 01-APR-14
If you want to get all records from April that includes those with time-components in the date fields, you should use the first day of the next month as the second side of the between clause:
select * from date_temp where temp between '01-APR-2014' and '01-MAY-2014';
01-APR-14
30-APR-14
Here's my original question:
merging two data sets
Unfortunately I omitted some intircacies, that I'd like to elaborate here.
So I have two tables events_source_1 and events_source_2 tables. I have to produce the data set from those tables into resultant dataset (that I'd be able to insert into third table, but that's irrelevant).
events_source_1 contain historic event data and I have to do get the most recent event (for such I'm doing the following:
select event_type,b,c,max(event_date),null next_event_date
from events_source_1
group by event_type,b,c,event_date,null
events_source_2 contain the future event data and I have to do the following:
select event_type,b,c,null event_date, next_event_date
from events_source_2
where b>sysdate;
How to put outer join statement to fill the void (i.e. when same event_type,b,c found from event_source_2 then next_event_date will be filled with the first date found
GREATLY APPRECIATE FOR YOUR HELP IN ADVANCE.
Hope I got your question right. This should return the latest event_date of events_source_1 per event_type, b, c and add the lowest event_date of event_source_2.
Select es1.event_type, es1.b, es1.c,
Max(es1.event_date),
Min(es2.event_date) As next_event_date
From events_source_1 es1
Left Join events_source_2 es2 On ( es2.event_type = es1.event_type
And es2.b = es1.b
And es2.c = es1.c
)
Group By c1.event_type, c1.b, c1.c
You could just make the table where you need to select a max using a group by into a virtual table, and then do the full outer join as I provided in the answer to the prior question.
Add something like this to the top of the query:
with past_source as (
select event_type, b, c, max(event_date)
from event_source_1
group by event_type, b, c, event_date
)
Then you can use past_source as if it were an actual table, and continue your select right after the closing parens on the with clause shown.
I end up doing two step process: 1st step populates the data from event table 1, 2nd step MERGES the data between target (the dataset from 1st step) and another source. Please forgive me, but I had to obfuscate table name and omit some columns in the code below for legal reasons. Here's the SQL:
INSERT INTO EVENTS_TARGET (VEHICLE_ID,EVENT_TYPE_ID,CLIENT_ID,EVENT_DATE,CREATED_DATE)
select VEHICLE_ID, EVENT_TYPE_ID, DEALER_ID,
max(EVENT_INITIATED_DATE) EVENT_DATE, sysdate CREATED_DATE
FROM events_source_1
GROUP BY VEHICLE_ID, EVENT_TYPE_ID, DEALER_ID, sysdate;
Here's the second step:
MERGE INTO EVENTS_TARGET tgt
USING (
SELECT ee.VEHICLE_ID VEHICLE_ID, ee.POTENTIAL_EVENT_TYPE_ID POTENTIAL_EVENT_TYPE_ID, ee.CLIENT_ID CLIENT_ID,ee.POTENTIAL_EVENT_DATE POTENTIAL_EVENT_DATE FROM EVENTS_SOURCE_2 ee WHERE ee.POTENTIAL_EVENT_DATE>SYSDATE) src
ON (tgt.vehicle_id = src.VEHICLE_ID AND tgt.client_id=src.client_id AND tgt.EVENT_TYPE_ID=src.POTENTIAL_EVENT_TYPE_ID)
WHEN MATCHED THEN
UPDATE SET tgt.NEXT_EVENT_DATE=src.POTENTIAL_EVENT_DATE
WHEN NOT MATCHED THEN
insert (tgt.VEHICLE_ID,tgt.EVENT_TYPE_ID,tgt.CLIENT_ID,tgt.NEXT_EVENT_DATE,tgt.CREATED_DATE) VALUES (src.VEHICLE_ID, src.POTENTIAL_EVENT_TYPE_ID, src.CLIENT_ID, src.POTENTIAL_EVENT_DATE, SYSDATE)
;