I need to write a stored procedure or SQL statements which needs to be run for around 1M records for an Oracle database. This should fetch the data based on priority as defined.
1 is highest priority and 4 is lowest.
When the records are group by using Cust ID, it should select only that record which is of highest priority as per source name else move to next source for priority within that group.
I am using old school ways by using LISTAGG and then check for value of Source name = A and then fetch all the data.
Is there any better way to extract the information.
The output should only contain records as per priority for each Group BY of Cust ID
You can use the analytical function ROW_NUMBER as follows:
SELECT * FROM
(SELECT T.*, ROW_NUMBER() OVER (PARTITION BY T.CUSTID ORDER BY P.PRIORITY) AS RN
FROM YOUR_TABLE T JOIN PRIORITY_TABLE P
ON T.SOURCE_NAME = P.SOURCE_NAME)
WHERE RN = 1
Related
for example i have data like this(sql server)
id name
4 anu
3 lohi
1 pras
2 chand
i want 2nd record in a table (means 3 lohi)
if i use row_number() function its changes the order and i get (2 chand)
i want 2nd record from table data
can anyonr please give me the query fro above scenario
There is no such thing as the nth row in a table. And for a simple reason: SQL tables represent unordered sets (technically multi-sets because they allow duplicates).
You can do what you want use offset/fetch:
select t.*
from t
order by id desc
offset 1 fetch first 1 row only;
This assumes that the descending ordering on id is what you want, based on your example data.
You can also do this using row_number():
select t.*
from (select t.*,
row_number() over (order by id desc) as seqnum
from t
) t
where seqnum = 2;
I should note that that SQL Server allows you to assign row_number() without having an effective sort using something like this:
select t.*
from (select t.*,
row_number() over (order by (select NULL)) as seqnum
from t
) t
where seqnum = 2;
However, this returns an arbitrary row. There is no guarantee it returns the same row each time it runs, nor that the row is "second" in any meaningful use of the term.
I'm a new SQL user and need help.
Let's say I have a vehicle number 123 and I've traveled from Region 3 to final destination Region 4. In between, I've visited Region 1 and 5 as well but that's not my concern.
Simple example would be as follow.
Original Table
Desired Output
How can this be done in SQL query?
You have a sequence number so you can use some form of aggregation. One method is:
select records,
max(case when sequence = 1 then fromregion end) as fromregion,
max(case when sequence = maxsequence then toregion) as toregion
from (select t.*, max(sequence) over (partition by records) as max_sequence
from t
) t
group by records;
Unfortunately, SQL Server doesn't offer "first()" or "last()" as aggregation functions. But it does support first_value() as a window function. This allows you to do the logic without a subquery:
select distinct records,
first_value(fromRegion) over (partition by records order by sequence) as fromregion,
first_value(toRegion) over (partition by records order by sequence desc) as toregion
from t;
I am refactoring a stored procedure and I have the following issue:
I have this statement:
SELECT Top 1 unit_gid
FROM Some_Table
WHERE group_gid = #i_group_gid
ORDER BY effective_date desc
Now instead of supplying one group gid as a single parameter like in the above I wish to apply this statement to a collection of group gids which I have stored as a single column table.
So if I supply a list of 20 group gids I want to return a list 20 unit gids, the most recent one for each of those supplied group gids.
How can I do this without resorting to using loops? Is there a way that I can do it with CTEs for example?
You could join on the tables of gids, and use the row_number window function to get the most recent unit_gid per gid:
SELECT gid, unit_gid
FROM (SELECT s.gid AS gid,
unit_gid,
ROW_NUMBER() OVER (PARTITION BY gid ORDER BY effective_date DESC) rn
FROM some_table s
JOIN gids g ON s.gid = gids.gid) t
WHERE rn = 1
In the process of query optimization I got to following SQL query:
select s.*
from
(
select id, DATA, update_dt, inspection_dt, check_dt
RANK OVER()
(PARTITION by ID
ORDER BY update_dt DESC, DATA) rank
FROM TABLE
where update_dt < inspection_dt or update_dt < check_dt
) r
where r.rank = 1
Query returns the DATA that corresponds to the latest check_dt.
However, what I want to get is:
1. DATA corresponding to latest check_dt
2. DATA corresponding to latest inspection_dt.
One of the trivial solutions - just write two separate queries with a where single condition - one for inspection_dt, and one for check_dt. However, that way it loses initial intent - to shorten the running time.
By observing the source data I noticed the way to implement it - check date is always later than inspection date; knowing that I could just extract the record with the rank = 1 and it will give me DATA corresponding to latest CHECK_DT, and record with the largest rank would correspond to INSPECTION.
However, data I'm afraid data will not be always consistent, so I was looking for more abstract solution.
How about this?
select s.*
from (select id, DATA, update_dt, inspection_dt, check_dt,
RANK() OVER (PARTITION by ID
ORDER BY update_dt DESC, DATA
) as rank_upd,
RANK() OVER (PARTITION by ID
ORDER BY inspection_dt DESC, DATA
) as rank_insp,
FROM TABLE
) r
where r.rank_upd = 1 or r.rank_insp = 1;
I am trying to select the max dates on a field with other tables, to only give me one distinct row for the max date and not other rows with other dates. the code i have for max is
SELECT DISTINCT
Cust.CustId,
LastDate=(Select Max(Convert(Date,TreatmentFieldHstry.TreatmentDateTime))
FROM TreatmentFieldHstry
WHERE Cust.CustSer = Course.CustSer
AND Course.CourseSer = Session.CourseSer
AND Session.SessionSer = TreatmentFieldHstry.SessionSer)
This gives multiple rows depending on how many dates - i just want one for the max - can anyone help with this?
Thanks
You didn't specify exactly what database and version you're using - but if you're on SQL Server 2005 or newer, you can use something like this (a CTE with the ROW_NUMBER ranking function) - I've simplified it a bit, since I don't know what those other tables are that you have in your select, that don't ever show up in any of the SELECT column lists.....
;WITH TopData AS
(
SELECT c.CustId, t.TreatmentDateTime,
ROW_NUMBER() OVER(PARTITION BY c.CustId ORDER BY t.TreatmentDateTime DESC) AS 'RowNum'
FROM
dbo.TreatmentFieldHstry t
INNER JOIN
dbo.Customer c ON c.CustId = t.CustId -- or whatever JOIN condition you have
WHERE
c.CustSer = Course.CustSer
)
SELECT
*
FROM
TopData
WHERE
RowNum = 1
Basically, the CTE (Common Table Expression) partitions your data by CustId and order by TreatmentDateTime (descending - newest first) - and numbers every entry with a consecutive number - for each "partition" (e.g. for each new value of CustId). With this, the newest entry for each customer has RowNum = 1 which is what I use to select it from that CTE.