I need to compare current row and previous row and based on some comparision need to derive a column value. Currently apporach I m following is making two differnt record sets and then use rank function and then by joining rank functions I m able to achiieve this. However, this seems to be tedious apporach, is there a better way to achieve this. I m currently writing query something like below :-
select
< comparing columns from two record sets and deriving column value>
(
select(<some complex logic>, rank from a) rcdset,
(select <some complex logic>, rank +1 from a) rcdset2 where rcdset.rnk = rcdset1.rnk (+)
Database - Oracle 10g
Use LAG(value_expr) OVER (ORDER BY rank_col) to retrieve the value (value_expr) from previous row (order defined by rank_col), see http://oracle-base.com/articles/misc/lag-lead-analytic-functions.php
Related
Have a query that uses double select (with select max) to fetch the row with the latest 'calculation_time' column among multiple rows which can have the same 'patient_set_id'. If there are multiple rows with the same 'patient_set_id', only the row with the latest 'calculation_time' should be retrieved. Calculation time is a date.
So far I've tried this but I'm not really sure if there is any better way for this, maybe using ORDER BY. But I'm very new to sql and need to know which one would be the fastest and more appropriate?
SELECT median from diagnostic_risk_stats WHERE
calculation_time=(SELECT MAX(calculation_time) FROM diagnostic_risk_stats WHERE
patient_set_id = UNHEX(REPLACE('5a9dbfca-74d6-471a-af27-31beb4b53bb2', "-","")));
You can use not exists as follows:
SELECT median
from diagnostic_risk_stats t
WHERE not exists
(Select 1 from diagnostic_risk_stats tt
Where t.patient_set_id = tt.patient_set_id
And tt.calculation_time > t.calculation_time)
And t.patient_set_id = UNHEX(REPLACE('5a9dbfca-74d6-471a-af27-31beb4b53bb2', "-",""));
I am new to the world of SQL queries, I am comfortable writing basic sql queries limited to to CRUD operations.
I am now working on a project where I have to write complex queries and I am seeking help on how to do it.
Scenario
I have a table x
The logic I need to implement is
The first record starts with some default value let us say 0 as StartCount.
I need to add numbers Add1+Add2 and deduct Minus
The result of step 2+StartCount becomes my EndCount
The next Month StartCount is the EndCount of the previous row.
I have to repeat step 2,3,4 for all the rows in the table.
How can I do this using SQL
You want a cumulative sum, is available using window/analytic functions. It is something like this:
select x.*,
(first_value(startcount) over (order by <ordercol>) +
sum(add1 + add2 - minus) over (order by <ordercol>)
) as yourvalue
from x;
<ordercol> is needed because SQL tables represent unordered sets. You need a column that specifies the ordering of the rows.
I need to figure out how to eliminate older revisions from my query's results, my database stores orders as 'Q000000' and revisions have an appended '-number'. My query currently is as follows:
SELECT DISTINCT Estimate.EstimateNo
FROM Estimate
INNER JOIN EstimateDetails ON EstimateDetails.EstimateID = Estimate.EstimateID
INNER JOIN EstimateDoorList ON EstimateDoorList.ItemSpecID = EstimateDetails.ItemSpecID
WHERE (Estimate.SalesRepID = '67' OR Estimate.SalesRepID = '61') AND Estimate.EntryDate >= '2017-01-01 00:00:00.000' AND EstimateDoorList.SlabSpecies LIKE '%MDF%'
ORDER BY Estimate.EstimateNo
So for instance, the results would include:
Q120455-10
Q120445-11
Q121675-2
Q122361-1
Q123456
Q123456-1
From this, I need to eliminate 'Q120455-10' because of the presence of '-11' for that order, and 'Q123456' because of the presence of the '-1' revision. I'm struggling greatly with figuring out how to do this, my immediate thought was to use case statements but I'm not sure what is the best way to implement them and how to filter. Thank you in advance, let me know if any more information is needed.
First you have to parse your EstimateNo column into sequence number and revision number using CHARINDEX and SUBSTRING (or STRING_SPLIT in newer versions) and CAST/CONVERT the revision to a numeric type
SELECT
SUBSTRING(Estimate.EstimateNo,0,CHARINDEX('-',Estimate.EstimateNo)) as [EstimateNo],
CAST(SUBSTRING(Estimate.EstimateNo,CHARINDEX('-',Estimate.EstimateNo)+1, LEN(Estimate.EstimateNo)-CHARINDEX('-',Estimate.EstimateNo)+1) as INT) as [EstimateRevision]
FROM
...
You can then use
APPLY - to select TOP 1 row that matches the EstimateNo or
Window function such as ROW_NUMBER to select only records with row number of 1
For example, using a ROW_NUMBER would look something like below:
SELECT
ROW_NUMBER() OVER(PARTITION BY EstimateNo ORDER BY EstimateRevision DESC) AS "LastRevisionForEstimate",
-- rest of the needed columns
FROM
(
-- query above goes here
)
You can then wrap the query above in a simple select with a where predicate filtering out a specific value of LastRevisionForEstimate, for instance
SELECT --needed columns
FROM -- result set above
WHERE LastRevisionForEstimate = 1
Please note that this is to a certain extent, pseudocode, as I do not have your schema and cannot test the query
If you dislike the nested selects, check out the Common Table Expressions
I read many threads but didn't get the right solution to my problem. It's comparable to this Thread
I have a query, which gathers data and writes it per shell script into a csv file:
SELECT
'"Dose History ID"' = d.dhs_id,
'"TxFieldPoint ID"' = tp.tfp_id,
'"TxFieldPointHistory ID"' = tph.tph_id,
...
FROM txfield t
LEFT JOIN txfielpoint tp ON t.fld_id = tp.fld_id
LEFT JOIN txfieldpoint_hst tph ON fh.fhs_id = tph.fhs_id
...
WHERE d.dhs_id NOT IN ('1000', '10000')
AND ...
ORDER BY d.datetime,...;
This is based on an very big database with lots of tables and machine values. I picked my columns of interest and linked them by their built-in table IDs. Now I have to reduce my result where I get many rows with same values and just the IDs are changed. I just need one(first) row of "tph.tph_id" with the mechanics like
WHERE "Rownumber" is 1
or something like this. So far i couldn't implement a proper subquery or use the ROW_NUMBER() SQL function. Your help would be very appreciated. The Result looks like this and, based on the last ID, I just need one row for every og this numbers (all IDs are not strictly consecutive).
A01";261511;2843119;714255;3634457;
A01";261511;2843113;714256;3634457;
A01";261511;2843113;714257;3634457;
A02";261512;2843120;714258;3634464;
A02";261512;2843114;714259;3634464;
....
I think "GROUP BY" may suit your needs.
You can group rows with the same values for a set of columns into a single row
I have the below query. The problem is the last column productdesc is returning two records and the query fails because of distinct. Now i need to add one more column in where clause of the select query so that it returns one record. The issue is that the column i need
to add should not be a part of group by clause.
SELECT product_billing_id,
billing_ele,
SUM(round(summary_net_amt_excl_gst/100)) gross,
(SELECT DISTINCT description
FROM RES.tariff_nt
WHERE product_billing_id = aa.product_billing_id
AND billing_ele = aa.billing_ele) productdescr
FROM bil.bill_sum aa
WHERE file_id = 38613 --1=1
AND line_type = 'D'
AND (product_billing_id, billing_ele) IN (SELECT DISTINCT
product_billing_id,
billing_ele
FROM bil.bill_l2 )
AND trans_type_desc <> 'Change'
GROUP BY product_billing_id, billing_ele
I want to modify the select statement to the below way by adding a new filter to the where clause so that it returns one record .
(SELECT DISTINCT description
FROM RRES.tariff_nt
WHERE product_billing_id = aa.product_billing_id
AND billing_ele = aa.billing_ele
AND (rate_structure_start_date <= TO_DATE(aa.p_effective_date,'yyyymmdd')
AND rate_structure_end_date > TO_DATE(aa.p_effective_date,'yyyymmdd'))
) productdescr
The aa.p_effective_date should not be a part of GROUP BY clause. How can I do it? Oracle is the Database.
So there are multiple RES.tariff records for a given product_billing_id/billing_ele, differentiated by the start/end dates
You want the description for the record that encompasses the 'p_effective_date' from bil.bill_sum. The kicker is that you can't (or don't want to) include that in the group by. That suggests you've got multiple rows in bil.bill_sum with different effective dates.
The issue is what do you want to happen if you are summarising up those multiple rows with different dates. Which of those dates do you want to use as the one to get the description.
If it doesn't matter, simply use MIN(aa.p_effective_date), or MAX.
Have you looked into the Oracle analytical functions. This is good link Analytical Functions by Example