I have a table t1 with two int fields(id,month) and I have populated it with some values.
What I would like to see as an output is, the maximum of (count of id in a month). I have tried the following code and it works fine:
select id,max(freq) as maxfreq from
(select id,month,count(*) as freq
from t1
group by id,month) a
group by id
order by maxfreq desc
The result is:
ID MAXFREQ
1 3
2 3
3 1
4 1
This is fine. How to achieve this using the over partition by clause? And which one is more efficient? In reality my table consists of several thousands of records. So doing a subquery wont be a good idea I guess! Thanks for any help. Here's the fiddle
;WITH tmp AS (select id, row_number() over (partition by id, month order by id) rn
FROM t1)
SELECT t.id, max(tmp.rn) as maxfreq
from t1 t
INNER JOIN tmp ON tmp.id = t.id
GROUP BY t.id
You can try this -
select id,max(freq) as maxfreq from
(select id,row_number() over (partition by id,month ORDER BY id) as freq
from t1
) a
group by id
order by id,maxfreq desc
but from a performance standpoint, I do not see much difference between your original query and this one.
Same solution but with using CTE.
Actually there is no point to forcibly use windowing functions to this issue.
Compare both solutions with plan explorer.
;with c1 as
( select id,month,count(*) as freq
from t1
group by id,month
)
select id, max(freq) as maxfreq
from c1
group by id
order by maxfreq desc;
Related
I am stuck with this. I have a simple set-up with two tables. One table is holding emailaddresses one table is holding vouchercodes. I want to join them in a third table, so that each emailaddress has one random vouchercode.
Unfortunatly I am stuck with this as there are no identic Ids to match both values. What I have so far brings no result:
Select
A.Email
B.CouponCode
FROM Emailaddresses as A
JOIN CouponCodes as B
on A.Email = B.CouponCode
A hint would be great as search did not bring me any further yet.
Edit -
Table A (Addresses)
-------------------
Column A | Column B
-------------------------
email1#gmail.com True
email2#gmail.com
email3#gmail.com True
email4#gmail.com
Table B (Voucher)
-------------------
ABCD1234
ABCD5678
ABCD9876
ABCD5432
Table C
-------------------------
column A | column B
-------------------------
email1#gmail.com ABCD1234
email2#gmail.com ABCD5678
email3#gmail.com ABCD9876
email4#gmail.com ABCD5432
Sample Data:
While joining without proper keys is not a good solution, for your case you can try this. (note: not tested, just a quick suggestion)
;with cte_email as (
select row_number() over (order by Email) as rownum, Email
from Emailaddresses
)
;with cte_coupon as (
select row_number() over (order by CouponCode) as rownum, CouponCode
from CouponCodes
)
select a.Email,b.CouponCode
from cte_email a
join cte_coupon b
on a.rownum = b.rownum
You want to randomly join records, one email with one coupon each. So create random row numbers and join on these:
select
e.email,
c.couponcode
from (select t.*, row_number() over (order by newid()) as rn from emailaddresses t) e
join (select t.*, row_number() over (order by newid()) as rn from CouponCodes t) c
on c.rn = e.rn;
Give a row number for both the tables and join it with row number.
Query
;with cte as(
select [rn] = row_number() over(
order by [Column_A]
), *
from [Table_A]
),
cte2 as(
select [rn] = row_number() over(
order by [Column_A]
), *
from [Table_B]
)
select t1.[Column_A] as [Email_Id], t2.[Column_A] as [Coupon]
from cte t1
join cte2 t2
on t1.rn = t2.rn;
Find a demo here
I have a large set of measurements taken every 1 millisecond stored in a SQL Server 2012 table. Whenever there are 3 or more duplicate values in some rows that I would like to delete the middle duplicates. Highlighted values in this image of sample data are the ones that I want to delete. Is there a way to do this with a SQL query?
You can do this using a CTE and ROW_NUMBER:
SQL Fiddle
WITH CteGroup AS(
SELECT *,
grp = ROW_NUMBER() OVER(ORDER BY MS) - ROW_NUMBER() OVER(PARTITION BY Value ORDER BY MS)
FROM YourTable
),
CteFinal AS(
SELECT *,
RN_FIRST = ROW_NUMBER() OVER(PARTITION BY grp, Value ORDER BY MS),
RN_LAST = ROW_NUMBER() OVER(PARTITION BY grp, Value ORDER BY MS DESC)
FROM CteGroup
)
DELETE
FROM CteFinal
WHERE
RN_FIRST > 1
AND RN_LAST > 1
I'm sure there must be a more efficient way to do this, but you could join the table to itself twice to find the previous and next value in the list, and then delete all of the entries where all three values are the same.
DELETE FROM tbl
WHERE ms IN
(
SELECT T.ms
FROM tbl T
INNER JOIN tbl T1 ON T.ms = T1.ms + 1
INNER JOIN tbl T2 ON T.ms = T2.ms - 1
WHERE T.value = T1.value AND T.value = T2.value
)
If the table is really big, I can see this blowing tempdb though.
Yes there is
select * from table group by table.field ->value
does anyone know how can I subtract top two rows from one column only using one id? Here's my sample query:
SELECT top 2 a.consumption,
coalesce(a.consumption -
(SELECT b.consumption
FROM tbl_t_billing b
WHERE b.id = a.id + 1), a.consumption) AS diff
FROM tbl_t_billing a
WHERE a.customerId = '5'
ORDER BY a.dateCreated DESC
I want to know how to get the difference between the top 2 rows using one id from the consumption column using the customerId #5. I've tried but I can't get the right query for that. Can somebody help me please? Thanks!
try this:
;with cte as
(
select consumption, customerId,
row_number() over (partiton by customerid order by datecreated desc) rn
from tbl_t_billing where customerId = '5'
)
select a.customerId, a.consumption,
coalesce((a.consumption - b.consumption), a.consumption) consumption_diff
from cte a left outer join cte b on a.rn + 1 = b.rn
where a.rn = 1
declare #tbl_t_billing table(consumption int, customerId int, datecreated datetime)
insert into #tbl_t_billing
values
(10,5,'20100101'),
(7,5,'20000101'),
(9,4,'20100101'),
(5,4,'20000101'),
(8,3,'20100101'),
(3,3,'20000101'),
(7,2,'20100101'),
(3,2,'20000101'),
(4,1,'20100101'),
(2,1,'20000101')
-- get the difference between the last two consumption values for each customerId
select
customerId,
sum(consumption) diff
from(
select
customerId,
consumption *
case row_number() over(partition by customerId order by datecreated desc)
when 1 then 1 when 2 then -1
end consumption
from #tbl_t_billing
) t
group by customerId
When I run the code below the ROWID is always 1.
I need to the ID to start at 1 for each item with the same Credit Value.
;WITH CTETotal AS (SELECT
TranRegion
,TranCustomer
,TranDocNo
,SUM(TranSale) 'CreditValue'
FROM dbo.Transactions
LEFT JOIN customers AS C
ON custregion = tranregion
AND custnumber = trancustomer
LEFT JOIN products AS P
ON prodcode = tranprodcode
GROUP BY
TranRegion
,TranCustomer
,TranDocNo)
SELECT
r.RegionDesc
,suppcodedesc
,t.tranreason as [Reason]
,t.trandocno as [Document Number]
,sum(tranqty) as Qty
,sum(tranmass) as Mass
,sum(transale) as Sale
,cte.CreditValue AS 'Credit Value'
,RANK() OVER (PARTITION BY cte.CreditValue ORDER BY cte.CreditValue)AS ROWID
FROM transactions t
LEFT JOIN dbo.Regions AS r
ON r.RegionCode = TranRegion
LEFT JOIN CTETotal AS cte
ON cte.TranRegion = t.TranRegion
AND cte.TranCustomer = t.TranCustomer
AND cte.TranDocNo = t.TranDocNo
GROUP BY
r.RegionDesc
,suppcodedesc
,t.tranreason
,t.trandocno
,cte.CreditValue
ORDER BY CreditValue ASC
EDIT
All the credit values with 400 must have the ROWID set to 1. And all the credit values with 200 must have the ROWID set to 2. And so on and so on.
Do you need something like this?
with cte (item,CreditValue)
as
(
select 'a',8 as CreditValue union all
select 'b',18 union all
select 'a',8 union all
select 'b',18 union all
select 'a',8
)
select CreditValue,dense_rank() OVER (ORDER BY item)AS ROWID from cte
Result
CreditValue ROWID
----------- --------------------
8 1
8 1
8 1
18 2
18 2
In your code replace
,RANK() OVER (PARTITION BY cte.CreditValue ORDER BY cte.CreditValue)AS ROWID
by
,DENSE_RANK() OVER (ORDER BY cte.CreditValue)AS ROWID
You just don't have to use PARTITION, just DENSE_RANK() OVER (ORDER BY cte.CreditValue)
I think the problem is with the RANK() OVER (PARTITION BY clause
you have to partition it by item not by CreditValue
Try this
RANK() OVER (PARTITION BY cte.CreditValue ORDER BY cte.RegionDesc)AS ROWID
Edit: The issue here isn't actually the nesting of the subquery, it's potentially based on partition by having columns that truly make each row unique (or 1)
Rather than ranking within your complex query like this
select
rank() over(partition by...),
*
from
data_source
join table1
join table2
join table3
join table4
order by
some_column
Try rank() or row_number() on the resulting data set, not within it.
For example, using the query above, remove rank() and implement it this way:
select
rank() over(partition by...),
results.*
from (
select
*
from
data_source
join table1
join table2
join table3
join table4
order by
some_column
) as results
I have two columns:
namecode name
050125 chris
050125 tof
050125 tof
050130 chris
050131 tof
I want to group by namecode, and return only the name with the most number of occurrences. In this instance, the result would be
050125 tof
050130 chris
050131 tof
This is with SQL Server 2000
I usually use ROW_NUMBER() to achieve this. Not sure how it performs against various data sets, but we haven't had any performance issues as a result of using ROW_NUMBER.
The PARTITION BY clause specifies which value to "group" the row numbers by, and the ORDER BY clause specifies how the records within each "group" should be sorted. So partition the data set by NameCode, and get all records with a Row Number of 1 (that is, the first record in each partition, ordered by the ORDER BY clause).
SELECT
i.NameCode,
i.Name
FROM
(
SELECT
RowNumber = ROW_NUMBER() OVER (PARTITION BY t.NameCode ORDER BY t.Name),
t.NameCode,
t.Name
FROM
MyTable t
) i
WHERE
i.RowNumber = 1;
select distinct namecode
, (
select top 1 name from
(
select namecode, name, count(*)
from myTable i
where i.namecode = o.namecode
group by namecode, name
order by count(*) desc
) x
) as name
from myTable o
SELECT max_table.namecode, count_table2.name
FROM
(SELECT namecode, MAX(count_name) AS max_count
FROM
(SELECT namecode, name, COUNT(name) AS count_name
FROM mytable
GROUP BY namecode, name) AS count_table1
GROUP BY namecode) AS max_table
INNER JOIN
(SELECT namecode, COUNT(name) AS count_name, name
FROM mytable
GROUP BY namecode, name) count_table2
ON max_table.namecode = count_table2.namecode AND
count_table2.count_name = max_table.max_count
I did not try but this should work,
select top 1 t2.* from (
select namecode, count(*) count from temp
group by namecode) t1 join temp t2 on t1.namecode = t2.namecode
order by t1.count desc
Here are to examples that you could use but the temp table use is more efficient than the view, but was done on a small data sample. You would want to check your own statistics.
--Creating A View
GO
CREATE VIEW StateStoreSales AS
SELECT t.state,t.stor_id,t.stor_name,SUM(s.qty) 'TotalSales'
,ROW_NUMBER() OVER (PARTITION BY t.state ORDER BY SUM(s.qty) DESC) AS 'Rank'
FROM [dbo].[sales] s
JOIN [dbo].[stores] t ON (s.stor_id = t.stor_id)
GROUP BY t.state,t.stor_id,t.stor_name
GO
SELECT * FROM StateStoreSales
WHERE Rank <= 1
ORDER BY TotalSales Desc
DROP VIEW StateStoreSales
---Using a Temp Table
SELECT t.state,t.stor_id,t.stor_name,SUM(s.qty) 'TotalSales'
,ROW_NUMBER() OVER (PARTITION BY t.state ORDER BY SUM(s.qty) DESC) AS 'Rank' INTO #TEMP
FROM [dbo].[sales] s
JOIN [dbo].[stores] t ON (s.stor_id = t.stor_id)
GROUP BY t.state,t.stor_id,t.stor_name
SELECT * FROM #TEMP
WHERE Rank <= 1
ORDER BY TotalSales Desc
DROP TABLE #TEMP