SQL: Pinned rows and row number calculation - sql

Question

We have a requirement to assign row number to all rows using following rule
Row if pinned should have same row number
Otherwise sort it by GMD
Example:
ID GMD IsPinned
1 2.5 0
2 0 1
3 2 0
4 4 1
5 3 0
Should Output
ID GMD IsPinned RowNo
5 3 0 1
2 0 1 2
1 2.5 0 3
4 4 1 4
3 2 0 5
Please Note row number for Id's 2 and 4 stayed intact as they are pinned with values of 2 and 4 respectively even though the GMD are not in any order
Rest of rows Id's 1, 3 and 5 row numbers are sorted using GMD desc
I tried using RowNumber SQL 2012 however, it is pushing pinned items from their position

Answer 1

Here's a set-based approach to solving this. Note that the first CTE is unnecessary if you already have a Numbers table in your database:
declare #t table (ID int,GMD decimal(5,2),IsPinned bit)
insert into #t (ID,GMD,IsPinned) values
(1,2.5,0), (2, 0 ,1), (3, 2 ,0), (4, 4 ,1), (5, 3 ,0)
;With Numbers as (
select ROW_NUMBER() OVER (ORDER BY ID) n from #t
), NumbersWithout as (
select
n,
ROW_NUMBER() OVER (ORDER BY n) as rn
from
Numbers
where n not in (select ID from #t where IsPinned=1)
), DataWithout as (
select
*,
ROW_NUMBER() OVER (ORDER BY GMD desc) as rn
from
#t
where
IsPinned = 0
)
select
t.*,
COALESCE(nw.n,t.ID) as RowNo
from
#t t
left join
DataWithout dw
inner join
NumbersWithout nw
on
dw.rn = nw.rn
on
dw.ID = t.ID
order by COALESCE(nw.n,t.ID)
Hopefully my naming makes it clear what we're doing. I'm a bit cheeky in the final SELECT by using a COALESCE to get the final RowNo when you might have expected a CASE expression. But it works because the contents of the DataWithout CTE is defined to only exist for unpinned items which makes the final LEFT JOIN fail.
Results:
ID GMD IsPinned RowNo
----------- --------------------------------------- -------- --------------------
5 3.00 0 1
2 0.00 1 2
1 2.50 0 3
4 4.00 1 4
3 2.00 0 5
Second variant that may perform better (but never assume, always test):
declare #t table (ID int,GMD decimal(5,2),IsPinned bit)
insert into #t (ID,GMD,IsPinned) values
(1,2.5,0), (2, 0 ,1), (3, 2 ,0), (4, 4 ,1), (5, 3 ,0)
;With Numbers as (
select ROW_NUMBER() OVER (ORDER BY ID) n from #t
), NumbersWithout as (
select
n,
ROW_NUMBER() OVER (ORDER BY n) as rn
from
Numbers
where n not in (select ID from #t where IsPinned=1)
), DataPartitioned as (
select
*,
ROW_NUMBER() OVER (PARTITION BY IsPinned ORDER BY GMD desc) as rn
from
#t
)
select
dp.ID,dp.GMD,dp.IsPinned,
CASE WHEN IsPinned = 1 THEN ID ELSE nw.n END as RowNo
from
DataPartitioned dp
left join
NumbersWithout nw
on
dp.rn = nw.rn
order by RowNo
In the third CTE, by introducing the PARTITION BY and removing the WHERE clause we ensure we have all rows of data so we don't need to re-join to the original table in the final result in this variant.

Answer 2

this will work:
CREATE TABLE Table1
("ID" int, "GMD" number, "IsPinned" int)
;
INSERT ALL
INTO Table1 ("ID", "GMD", "IsPinned")
VALUES (1, 2.5, 0)
INTO Table1 ("ID", "GMD", "IsPinned")
VALUES (2, 0, 1)
INTO Table1 ("ID", "GMD", "IsPinned")
VALUES (3, 2, 0)
INTO Table1 ("ID", "GMD", "IsPinned")
VALUES (4, 4, 1)
INTO Table1 ("ID", "GMD", "IsPinned")
VALUES (5, 3, 0)
SELECT * FROM dual
;
select * from (select "ID","GMD","IsPinned",rank from(select m.*,rank()over(order by
"ID" asc) rank from Table1 m where "IsPinned"=1)
union
(select "ID","GMD","IsPinned",rank from (select t.*,rank() over(order by "GMD"
desc)-1 rank from (SELECT * FROM Table1)t)
where "IsPinned"=0) order by "GMD" desc) order by rank ,GMD;
output:
2 0 1 1
5 3 0 1
1 2.5 0 2
4 4 1 2
3 2 0 3

Answer 3

Can you try this query
CREATE TABLE Table1
(ID int, GMD numeric (18,2), IsPinned int);
INSERT INTO Table1 (ID,GMD, IsPinned)
VALUES (1, 2.5, 0),
(2, 0, 1),
(3, 2, 0),
(4, 4, 1),
(5, 3, 0)
select *, row_number () over(partition by IsPinned order by (case when IsPinned =0 then GMD else id end) ) [CustOrder] from Table1

Answer 4

This took longer then I thought, the thing is row_number would take a part to resolve the query. We need to differentiate the row_numbers by id first and then we can apply the while loop or cursor or any iteration, in our case we will just use the while loop.
dbo.test (you can replace test with your table name)
1 2.5 False
2 0 True
3 3 False
4 4 True
6 2 False
Here is the query I wrote to achieve your result, I have added comment under each operation you should get it, if you have any difficultly let me know.
Query:
--user data table
DECLARE #userData TABLE
(
id INT NOT NULL,
gmd FLOAT NOT NULL,
ispinned BIT NOT NULL,
rownumber INT NOT NULL
);
--final result table
DECLARE #finalResult TABLE
(
id INT NOT NULL,
gmd FLOAT NOT NULL,
ispinned BIT NOT NULL,
newrownumber INT NOT NULL
);
--inserting to uer data table from the table test
INSERT INTO #userData
SELECT t.*,
Row_number()
OVER (
ORDER BY t.id ASC) AS RowNumber
FROM test t
--creating new table for ids of not pinned
CREATE TABLE #ids
(
rn INT,
id INT,
gmd FLOAT
)
-- inserting into temp table named and adding gmd by desc
INSERT INTO #ids
(rn,
id,
gmd)
SELECT DISTINCT Row_number()
OVER(
ORDER BY gmd DESC) AS rn,
id,
gmd
FROM #userData
WHERE ispinned = 0
--declaring the variable to loop through all the no pinned items
DECLARE #id INT
DECLARE #totalrows INT = (SELECT Count(*)
FROM #ids)
DECLARE #currentrow INT = 1
DECLARE #assigningNumber INT = 1
--inerting pinned items first
INSERT INTO #finalResult
SELECT ud.id,
ud.gmd,
ud.ispinned,
ud.rownumber
FROM #userData ud
WHERE ispinned = 1
--looping through all the rows till all non-pinned items finished
WHILE #currentrow <= #totalrows
BEGIN
--skipping pinned numers for the rows
WHILE EXISTS(SELECT 1
FROM #finalResult
WHERE newrownumber = #assigningNumber
AND ispinned = 1)
BEGIN
SET #assigningNumber = #assigningNumber + 1
END
--getting row by the number
SET #id = (SELECT id
FROM #ids
WHERE rn = #currentrow)
--inserting the non-pinned item with new row number into the final result
INSERT INTO #finalResult
SELECT ud.id,
ud.gmd,
ud.ispinned,
#assigningNumber
FROM #userData ud
WHERE id = #id
--going to next row
SET #currentrow = #currentrow + 1
SET #assigningNumber = #assigningNumber + 1
END
--getting final result
SELECT *
FROM #finalResult
ORDER BY newrownumber ASC
--dropping table
DROP TABLE #ids
Output: