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Avoiding loops in matching records


Avoiding loops in matching records

By : user2950845
Date : November 17 2020, 11:58 AM
I wish this helpful for you I'm trying to reduce a loop in SQL Server, and I'm kind of stumped. I need to pair buys and sells by a given criteria. For that criteria, a group of buys can match with a group of sells. Not every buy can match with every sell (and vice versa), but a single buy can match with more than one sell (and vice versa). I can easily get a temp table of all possible matches, but the hard part is pairing off a single buy to a single sell only only using each once. , Tough one! I think this works.
code :
CREATE TABLE #t (MatchID INT, BuyID INT, SellID INT)
INSERT  #t
SELECT 1, 91, 59 UNION ALL
SELECT 2, 91, 60 UNION ALL
SELECT 3, 97, 59 UNION ALL
SELECT 4, 97, 60


DELETE
  #t
WHERE
  MatchID IN 
(
  SELECT DISTINCT
    t1.MatchID
  FROM
    (
     SELECT
      MatchID,
      ROW_NUMBER() OVER (PARTITION BY SellID ORDER BY SellID) AS Row
     FROM
      #t
    ) AS t1
    CROSS JOIN 
    (
      SELECT
        MatchID,
        ROW_NUMBER() OVER (PARTITION BY BuyID ORDER BY BuyID) AS Row
      FROM
        #t
     ) AS t2
  WHERE
    t1.Row <> 1 AND
    t2.Row <> 1
)

SELECT * FROM #t


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R: avoiding loops while inserting records into a matrix

R: avoiding loops while inserting records into a matrix


By : Nitin Rajput
Date : March 29 2020, 07:55 AM
Any of those help I have a matrix m of zeros and a data-frame df containing records I want to insert into m. , Pass a matrix of indicies into m.
code :
index <- cbind(
    row = df$r,
    col = match(df$c, colnames(m))       
)

m[index] <- df$q
Returning linked records and avoiding multiple subqueries/loops

Returning linked records and avoiding multiple subqueries/loops


By : Stanley Gilstrap
Date : March 29 2020, 07:55 AM
wish helps you That sounds like a recursive query. You can read how that's done in SQL Server using Common Table Expressions (CTEs) here: http://technet.microsoft.com/en-us/library/ms186243(v=sql.105).aspx
Avoiding while loops

Avoiding while loops


By : user2841666
Date : March 29 2020, 07:55 AM
Hope that helps You don't need a loop for this purpose. You can solve it by using the following formula (moving average):
code :
(current_avg * current_innings + avg * x)/(current_innings + x) = goal_avg
avoiding for loops in F#

avoiding for loops in F#


By : Zac D
Date : March 29 2020, 07:55 AM
Hope this helps As I dont grasp what you are trying to accomplish my solution is just a bit of clean up
code :
let stringsAndNums = [("aa-",20); ("b1",20); ("aa",10); ("b12",10); ("+aa-",30)]
let results =
    let split (subject, value) = 
        let related =
            //first I created a named function for the filter expression
            let filtering (osubject:string, _) = osubject.Contains(subject) || subject.Contains(osubject) 
            stringsAndNums |> List.filter filtering 
        //accessing the 2 first items of a tuple can be done via fst, snd 
        let relvalues = related |> List.map snd 
        let min = (relvalues |> List.min)
        let max = (relvalues |> List.max) 
        //I assume you wanted to return that tuple so away with the printf
        (subject, value, min, max, (max - min))

    stringsAndNums |> List.map split

for result in results do
    //and lastly use printfn (n-for newline) so the printing is nicer
    printfn "%A" result
Query to Fetch Matching Records between 2 tables and not matching Null records from Second Tabl2

Query to Fetch Matching Records between 2 tables and not matching Null records from Second Tabl2


By : N'fa Ali Badara Mans
Date : March 29 2020, 07:55 AM
I think the issue was by ths following , I've 2 tables as below. I need to fetch the matching names between the 2 tables and also the unmatching NULL Records in the 2second table. The Column Number (key Vlaues) should be in Join . I used the below query. But is there any way to get rid of Union, or is there any other better way of writing the query than below? , As for me for this request is more convenient something like
code :
select distinct a.name from FirstTable a,SecondTable b
where a.number=b.number and a.name=nvl(b.name,a.name)
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