I'm trying to retrieve the max datetime of a task started, grouping by task_code.
I've tried the following query to get all the max date, but the date and time are two different fields, if I try to concatened like,
MAX(DATEINI||' '||HOURINI)
to get the latest datetime by group, the query return empty. Is possible to do this, am I missing something?
SELECT DATEINI||' '||HOURINI AS STARTED, TASK, TASK_CODE
FROM TB_TASKS WHERE DATEINI IN
(SELECT MAX(DATEINI) FROM TB_TASKS GROUP BY TASK_CODE)
ORDER BY DATEINI DESC, HOURINI DESC;
Try working with dates instead of strings like this:
SELECT DATEINI||' '||HOURINI AS STARTED, TASK, TASK_CODE
FROM TB_TASKS WHERE TO_DATE(DATEINI||' '||HOURINI,'DD/MM/YYYY HH:MI:SS') IN
(SELECT MAX(TO_DATE(DATEINI||' '||HOURINI,'DD/MM/YYYY HH:MI:SS')) FROM TB_TASKS GROUP BY TASK_CODE)
ORDER BY DATEINI DESC, HOURINI DESC;
Check that to_date format depends of your context.
Related
Just had a user answer this correctly for TSQL, but wondering how best to achieve this now in SQL Developer/PLSQL seeing as there is no DATEDIFF function.
Table I want to query on has some 'CODE' values, which can naturally have multiple primary key records ('OccsID') in a table 'Occs'. There is also a datetime column called 'CreateDT' for each OccsID.
Just want to find the maximum possible time variance between any 2 consecutive rows in 'Occs', per 'CODE'.
If you subtract the "next" date and "this" date (using the LEAD analytic function), you'll get the date difference. Then fetch the maximum difference per code. Something like this:
with diff as
(select occsid,
code,
nvl(lead(createdt) over (partition by code order by createdt), createdt) - createdt date_diff
from test
)
select code,
max(date_diff)
from diff
group by code;
Assuming that this T-SQL version works for you (from the prior question)
SELECT x.code, MAX(x.diff_sec) FROM
(
SELECT
code,
DATEDIFF(
SECOND,
CreateDT,
LEAD(CreateDT) OVER(PARTITION BY CODE ORDER BY CreateDT) --next row's createdt
) as diff_sec
FROM Occs
)x
GROUP BY x.code
The simplest option is just to subtract the two dates to get a difference in days. You can then multiply to get the difference in hours, minutes, or seconds
SELECT x.code, MAX(x.diff_day), MAX(x.diff_sec)
FROM
(
SELECT
code,
CreateDT -
LEAD(CreateDT) OVER(PARTITION BY CODE ORDER BY CreateDT) as diff_day,
24*60*60* (CreateDT -
LEAD(CreateDT) OVER(PARTITION BY CODE ORDER BY CreateDT)) as diff_sec
FROM Occs
)x
GROUP BY x.code
i have a select(water readings, previous water reading, other columns) , a "where clause" that is based on date water reading date. however for previous water reading it must not consider the where clause. I want to get previous meter reading regardless where clause date range.
looked at union problem is that i have to use the same clause,
SELECT
WATERREADINGS.name,
WATERREADINGS.date,
LAG( WATERREADINGS.meter_reading,1,NULL) OVER(
PARTITION BY WATERREADINGS.meter_id,WATERREADINGS.register_id
ORDER BY WATERREADINGS.meter_id DESC,WATERREADINGS.register_id
DESC,WATERREADINGS.readingdate ASC,WATERREADINGS.created ASC
) AS prev_water_reading,
FROM WATERREADINGS
WHERE waterreadings.waterreadingdate BETWEEN '24-JUN-19' AND
'24-AUG-19' and isactive = 'Y'
The prev_water_reading value must not be restricted by the date BETWEEN '24-JUN-19' AND '24-AUG-19' predicate but the rest of the sql should be.
You can do this by first finding the previous meter readings for all rows and then filtering those results on the date, e.g.:
WITH meter_readings AS (SELECT waterreadings.name,
waterreadings.date dt,
lag(waterreadings.meter_reading, 1, NULL) OVER (PARTITION BY waterreadings.meter_id, waterreadings.register_id
ORDER BY waterreadings.readingdate ASC, waterreadings.created ASC)
AS prev_water_reading,
FROM waterreadings
WHERE isactive = 'Y')
-- the meter_readings subquery above gets all rows and finds their previous meter reading.
-- the main query below then applies the date restriction to the rows from the meter_readings subquery.
SELECT name,
date,
prev_water_reading,
FROM meter_readings
WHERE dt BETWEEN to_date('24/06/2019', 'dd/mm/yyyy') AND to_date('24/08/2019', 'dd/mm/yyyy');
Perform the LAG in an inner query that is not filtered by dates and then filter by the dates in the outer query:
SELECT name,
"date",
prev_water_reading
FROM (
SELECT name,
"date",
LAG( meter_reading,1,NULL) OVER(
PARTITION BY meter_id, register_id
ORDER BY meter_id DESC, register_id DESC, readingdate ASC, created ASC
) AS prev_water_reading,
waterreadingdate --
FROM WATERREADINGS
WHERE isactive = 'Y'
)
WHERE waterreadingdate BETWEEN DATE '2019-06-24' AND DATE '2019-08-24'
You should also not use strings for dates (that require an implicit cast using the NLS_DATE_FORMAT session parameter, which can be changed by any user in their own session) and use date literals DATE '2019-06-24' or an explicit cast TO_DATE( '24-JUN-19', 'DD-MON-RR' ).
You also do not need to reference the table name for every column when there is only a single table as this clutters up your code and makes it difficult to read and DATE is a keyword so you either need to wrap it in double quotes to use it as a column name (which makes the column name case sensitive) or should use a different name for your column.
I've added a subquery with previous result without filter and then joined it with the main table with filters:
SELECT
WATERREADINGS.name,
WATERREADINGS.date,
w_lag.prev_water_reading
FROM
WATERREADINGS,
(SELECT name, date, LAG( WATERREADINGS.meter_reading,1,NULL) OVER(
PARTITION BY WATERREADINGS.meter_id,WATERREADINGS.register_id
ORDER BY WATERREADINGS.meter_id DESC,WATERREADINGS.register_id
DESC,WATERREADINGS.readingdate ASC,WATERREADINGS.created ASC
) AS prev_water_reading
FROM WATERREADINGS) w_lag
WHERE waterreadings.waterreadingsdate BETWEEN '24-JUN-19' AND '24-AUG-19' and isactive = 'Y'
and WATERREADINGS.name = w_lag.name
and WATERREADINGS.date = w_lag.date
Is there any method to reduce the time taken to get the result from below query?
Please help. Thanks in advance!
select status, count(distinct id)
from emp
where id >=
( select min(id)
from emp
where id >= (select max(id-200000) from emp)
and trunc(join_date) >= '01-Mar-2018')
group by status;
Use analytic functions - this will perform only a single table scan (whereas your query has three table/index scans):
SELECT status,
COUNT( DISTINCT id )
FROM (
SELECT status,
id,
MIN( CASE WHEN join_date >= DATE '2018-03-01' THEN id END ) OVER () AS min_id
FROM (
SELECT status,
id,
join_date,
MAX( id ) OVER () AS max_id
FROM emp
)
WHERE id >= max_id - 20000
)
WHERE id >= min_id
GROUP BY status;
Also, you can use a date literal (rather than relying on implicit conversion of a string to a date using the NLS_DATE_FORMAT session parameter) and you do not need to use the TRUNC() function (since that may prevent Oracle using an index on the join_date column and would instead require a function-based index).
It is important to know if id is a primary key (as columns with that name usually are) or not. If it is not, you definitely need an index on id for it to perform (and I would also wonder what the purpose of the column was). If id is the primary key, you don't need to the distinct as the values will be unique anyway.
The select min(id) sub-select is redundant as you already found max(id - 200000) so you don't need to know the first min(id) greater than that. You can just use >= by itself (with the condition on the date added). By the way, I would write max(id) - 200000 instead; on some databases, it might work better.
The date comparison may be problematic. You should try an index on join_date if you haven't got one already, but the trunc might stop that from being used, so it would be best to remove that and make the other side of the compare use a TO_TIMESTAMP or TO_DATE to generate a corresponding literal as appropriate, setting the time to midnight.
But there can be problems with comparing timestamps due to timezones, etc. I'd need to know more about your setup to know whether that is likely to be a problem.
I need to restrict a query with a
SELECT ... FROM ...
WHERE my_date=(RESULT FROM A SELECT)
... ;
in order to achieve that I am using as result of the select a timestamp (if I instead use a datetime I get nothing from my select probably because the format I am using trims the datetime at the second).
Sadly this is not working because these kindo of queries:
select DISTINCT TO_DATE(TO_TIMESTAMP(TO_DATE('25-10-2017 00:00', 'dd-MM-yyyy HH24:MI'))) from DUAL;
return an
ORA-01830: date format picture ends before converting entire input string
how to deal with timestamp to date conversion?
If you want to just compare and check only he dates use trunc on both LHS and RHS.
SELECT ... FROM ...
WHERE trunc(my_date)=(select trunc(RESULT) FROM A)
... ;
This will just compare the dates by truncating the timestamp values
You can use the combination of "TRUNC" and "IN" keywords in your query to achieve what you are expecting. Please check the below query sample as a reference.
SELECT * FROM customer WHERE TRUNC(last_update_dt) IN (select DISTINCT (TRUNC(last_update_dt)) from ... )
Cheers !!
I have a report that has two parameters, PM_DATE and PM_STOCK_ID. It's LOV query is
SELECT DISTINCT ID FROM STOCK_COUNT
I want to filter the parameter PM_STOCK_ID based on the date which user specifies in date parameter. In the where clause of LOV I tried using:
SELECT DISTINCT ID FROM STOCK_COUNT
WHERE TRUNC (SCHEDULE_DATE) = NVL (:PM_DATE, SCHEDULE_DATE)
but this didn't work.
I've also tried with a range using two parameters, P_SDATE (Start Date) and P_EDATE (End Date):
SELECT distinct id FROM STOCK_COUNT
WHERE
(TRUNC(SCHEDULE_DATE)) BETWEEN NVL(:P_SDATE, TRUNC(SCHEDULE_DATE)) AND NVL(:P_EDATE, TRUNC(SCHEDULE_DATE))
which gets error:
Parameter name: P_STOCK_ID Unparseable date: ""
How should I be doing this?
By just specifying the string :PM_DATE without a to_date function around it, you are getting implicit type conversion which is likely the root cause of the difficulty.