random row from diapason (1: n) in groups sql - sql

I need select random row from Table using groups and order, but random's row number in group should not be more then constant (for example const = 3).
What I mean:
id time x
1 10:20 1
1 11:21 9
1 16:14 4
1 08:13 8
2 01:20 2
2 21:13 0
For id=1 rows could be:
id time x
1 10:20 1
1 11:21 9
1 08:13 8
BUT not
1 16:14 4 because in order by time it's local number more than 3
for
Id= 2 - any row

WITH cte as (
SELECT *, ROW_NUMBER() OVER (partition by id ORDER BY RANNDOM()) as rn
FROM myTable
)
SELECT *
FROM cte
WHERE rn <= 3

Something like this:
SELECT distinct on (id) *
FROM (select
row_number() over (partition by id order by time ) as up_lim
from tab1) as a
WHERE row_number <= 3
ORDER by id, random() ;

Related

Find first N rows that have unique value with mod(id, N)

For example, N is 10 and a table looks like
id
1
2
3
4
5
6
7
10
11
12
13
108
109
111
112
113
Need to find first N rows that have unique value with mod(id, N).
Expected result is
mod10
1
2
3
4
5
6
7
10
108
109
I've tried something like
select *
from
(
select id, id % 10 as seq_id
from accounts order by id
) as s1
group by s1.seq_id limit 10;`
but not working.
You can use window function here -
SELECT id
FROM (SELECT id, ROW_NUMBER() OVER(PARTITION BY id % 10 ORDER BY id) RN
FROM table_name
) X
WHERE RN = 1
ORDER BY id
You can try the below one - using row_number()
DEMO
with cte as
(
select id, row_number() over(partition by seq_id order by id) as rn
from
(
select id, id % 10 as seq_id from tablename
)A
)
select id from cte where rn=1 order by id
OUTPUT:
id
1
2
3
4
5
6
7
10
108
109

What is the most efficient SQL query to find the max N values for every entities in a table

I wrote these 2 queries, the first one is keeping duplicates and the second one is dropping them
Does anyone know a more efficient way to achieve this?
Queries are for MSSQL, returning the top 3 values
1-
SELECT TMP.entity_id, TMP.value
FROM(
SELECT TAB.entity_id, LEAD(TAB.entity_id, 3, 0) OVER(ORDER BY TAB.entity_id, TAB.value) AS next_id, TAB.value
FROM mytable TAB
) TMP
WHERE TMP.entity_id <> TMP.next_id
2-
SELECT TMP.entity_id, TMP.value
FROM(
SELECT TMX.entity_id, LEAD(TMX.entity_id, 3, 0) OVER(ORDER BY TMX.entity_id, TMX.value) AS next_id, TMX.value
FROM(
SELECT TAB.entity_id, LEAD(TAB.entity_id, 1, 0) OVER(ORDER BY TAB.entity_id, TAB.value) AS next_id, TAB.value, LEAD(TAB.value, 1, 0) OVER(ORDER BY TAB.entity_id, TAB.value) AS next_value
FROM mytable TAB
) TMX
WHERE TMP.entity_id <> TMP.next_id OR TMX.value <> TMX.next_value
) TMP
WHERE TMP.entity_id <> TMP.next_id
Example:
Table:
entity_id value
--------- -----
1 9
1 11
1 12
1 3
2 25
2 25
2 5
2 37
3 24
3 9
3 2
3 15
Result Query 1 (25 appears twice for entity_id 2):
entity_id value
--------- -----
1 9
1 11
1 12
2 25
2 25
2 37
3 9
3 15
3 24
Result Query 2 (25 appears only once for entity_id 2):
entity_id value
--------- -----
1 9
1 11
1 12
2 5
2 25
2 37
3 9
3 15
3 24
You can use the ROW_NUMBER which will allow duplicates as follows:
select entity_id, value from
(select t.*, row_number() over (partition by entity_id order by value desc) as rn
from your_Table) where rn <= 3
You can use the rank to remove the duplicate as follows:
select distinct entity_id, value from
(select t.*, rank() over (partition by entity_id order by value desc) as rn
from your_Table) where rn <= 3

How to select top 2 values for each id

I have a table with values
id sales date
1 5 "2015-01-04"
1 3 "2015-01-03"
1 1 "2015-01-01"
1 1 "2015-01-01"
2 7 "2015-01-05"
2 6 "2015-01-04"
2 4 "2015-01-03"
3 11 "2015-01-08"
3 10 "2015-01-07"
3 9 "2015-01-06"
3 8 "2015-01-05"
I want to select top two values of each id as shown in desired output.
Desired output:
id sales date
1 5 "2015-01-04"
1 3 "2015-01-03"
2 7 "2015-01-05"
2 6 "2015-01-04"
3 11 "2015-01-08"
3 10 "2015-01-07"
My attempt:
can someone help me with this. Thank you in advance!
select transactions.salesperson_id, transactions.id, transactions.date
from transactions
ORDER BY transactions.salesperson_id ASC, transactions.date DESC;
This can be done using window functions:
select id, sales, "date"
from (
select id, sales, "date",
dense_rank() over (partition by id order by "date" desc) as rnk
from transactions
) t
where rnk <= 2;
If there are multiple rows on the same date this might return more than two rows for the same ID. If you don't want that, use row_number() instead of dense_rank()
row_number() will get what you want.
select * from
(select row_number() over (partition by id order by date) as rn, sales, date from transactions) t1
where t1.rn <= 2

Remove minimum rank rows in SQL Server

I have a table like below.
Customer Order Rank
1 12 3
1 14 7
2 15 6
2 16 4
2 17 2
2 21 1
3 24 5
3 25 6
3 27 7
Now, I want to select all rows except for rows with minimum ranks for each customer. It should look like below.
Customer Order Rank
1 14 7
2 15 6
2 16 4
2 17 2
3 25 6
3 27 7
You can use a CTE + ROW_NUMBER:
WITH CTE AS
(
SELECT Customer, [Order], Rank,
RN = ROW_NUMBER() OVER (PARTITION BY Customer ORDER BY Rank)
FROM dbo.Customers
)
SELECT Customer, [Order], Rank
FROM CTE
WHERE RN > 1
ORDER BY Customer, Rank DESC
Demo: http://sqlfiddle.com/#!6/444be/3/0
WITH CTE AS (
SELECT Customer,Order,Rank,
ROW_NUMBER() OVER (PARTITION BY Customer ORDER BY Rank ) as rn FROM t
)
SELECT Customer,Order,Rank FROM CTE
WHERE rn >1

Select and aggregate last records base on order

I have different versions of the charges in a table. I want to grab and sum the last charge grouped by Type.
So I want to add 9.87, 9.63, 1.65.
I want the Parent ID , sum(9.87 + 9.63 + 1.65) as the results of this query.
We use MSSQL
ID ORDER CHARGES TYPE PARENT ID
1 1 6.45 1 1
2 2 1.25 1 1
3 3 9.87 1 1
4 1 6.54 2 1
5 2 5.64 2 1
6 3 0.84 2 1
7 4 9.63 2 1
8 1 7.33 3 1
9 2 5.65 3 1
10 3 8.65 3 1
11 4 5.14 3 1
12 5 1.65 3 1
WITH recordsList
AS
(
SELECT Type, Charges,
ROW_NUMBER() OVER (PArtition BY TYPE
ORDER BY [ORDER] DESC) rn
FROM tableName
)
SELECT SUM(Charges) totalCharge
FROM recordsLIst
WHERE rn = 1
SQLFiddle Demo
Use row_number() to identify the rows to be summed, and then sum them:
select SUM(charges)
from (select t.*,
ROW_NUMBER() over (PARTITION by type order by id desc) as seqnum
from t
) t
where seqnum = 1
Alternatively you could use a window aggregate MAX():
SELECT SUM(Charges)
FROM (
SELECT
[ORDER],
Charges,
MaxOrder = MAX([ORDER]) OVER (PARTITION BY [TYPE])
FROM atable
) s
WHERE [ORDER] = MaxOrder
;
SELECT t.PARENT_ID, SUM(t.CHARGES)
FROM dbo.test73 t
WHERE EXISTS (
SELECT 1
FROM dbo.test73
WHERE [TYPE] = t.[TYPE]
HAVING MAX([ORDER]) = t.[ORDER]
)
GROUP BY t.PARENT_ID
Demo on SQLFiddle