Goal: Show the ID, title of the books and the pub. Year for the book with the highest sales amount; include ties. Use the total extended cost (quantity * order price) when determining the sales of a book.
Rules:
use subquery only
no joins
no union
only subquery
Query:
SELECT book_id,
title,
year_publd
FROM bkinfo.books
where book_id =
(
SELECT TOP 1 WITH TIES book_id, quantity*order_price as Extended_cost
from bkorders.order_details
order by quantity*order_price DESC
)
;
Error:
Msg 116, Level 16, State 1, Line 10 Only one expression can be
specified in the select list when the subquery is not introduced with
EXISTS.
The subquery shows the book_id with the highest amount but when running it as a whole, I receive an error. Please explain what I should do.
;with cte as
(
select book_id, quantity*order_price as Extended_cost from bkorders.order_details
order by Extended_cost DESC
)
select top 1 with ties * from cte
SELECT book_id, title, year_publd
FROM bkinfo.books
where book_id =
(
SELECT TOP 1 book_id
from bkorders.order_details
order by quantity*order_price DESC
)
;
Related
I have the following query:
SELECT *
FROM dbo.mytable FOR system_time BETWEEN #rowEffFrom AND #rowEffTo t
WHERE t.anothertableid = 1
ORDER BY t.rowefffrom
My table has the following columns relevant to this question:
Id, AnotherTableId (FK), Description, RowEffFrom, RowEffTo
What I have done is get an entry from tblAnotherTable's history matching certain criteria. I then set #rowEffFrom and #rowEffTo as the RowEffFrom and RowEffTo for the retrieved row (top 1).
myTable has a many to one relationship with tblAnotherTable.
I want to retrieve the latest version of all entries between the #rowEffFrom and #rowEffTo, but one per Id.
e.g.
if my query above returns 2 rows, both with Id of 11, then I just want the most recent. If it returns 6 rows with ids 11,12,13 I want 3 rows with the latest of each version.
Nevermind, the answer is:
SELECT *
FROM ( SELECT Row_number() OVER (partition BY id ORDER BY rowefffrom DESC) rownumber,
*
FROM dbo.mytable FOR system_time BETWEEN #rowEffFrom AND #rowEffTo t
WHERE t.anothertableid = 1 ) mt
WHERE mt.rownumber = 1
I have DB which having 5 column as follows:
message_id
user_id_send
user_id_rec
message_date
message_details
Looking for a SQL Serve Query, I want to Filter Results from two columns (user_id_send,user_id_rec)for Given User ID based on following constrains:
Get the Latest Record (filtered on date or message_id)
Only Unique Records (1 - 2 , 2 - 1 are same so only one record will be returned which ever is the latest one)
Ordered by Descending based on message_id
SQL Query
The main purpose of this query is to get records of user_id to find out to whom he has sent messages and from whom he had received messages.
I have also attached the sheet for your reference.
Here is my try
WITH t
AS (SELECT *
FROM messages
WHERE user_id_sender = 1)
SELECT DISTINCT user_id_reciever,
*
FROM t;
WITH h
AS (SELECT *
FROM messages
WHERE user_id_reciever = 1)
SELECT DISTINCT user_id_sender,
*
FROM h;
;WITH tmpMsg AS (
SELECT M2.message_id
,M2.user_id_receiver
,M2.user_id_sender
,M2.message_date
,M2.message_details
,ROW_NUMBER() OVER (PARTITION BY user_id_receiver+user_id_sender ORDER BY message_date DESC) AS 'RowNum'
FROM messages M2
WHERE M2.user_id_receiver = 1
OR M2.user_id_sender = 1
)
SELECT T.message_id
,T.user_id_receiver
,T.user_id_sender
,T.message_date
,T.message_details
FROM tmpMsg T
WHERE RowNum <= 1
The above should fetch you the results you are looking for when you query for a particular user_id (replace the 1 with parameter e.g. #p_user_id). The user_id_receiver+user_id_sender in the PARTITION clause ensure that records with user id combinations such as 1 - 2, 2 - 1 are not selected twice.
Hope this helps.
select * from
(
select ROW_NUMBER() over (order by message_date DESC) as rowno,
* from messages
where user_id_receiver = 1
--order by message_date DESC
) T where T.rowno = 1
UNION ALL
select * from
(
select ROW_NUMBER() over (order by message_date DESC) as rowno,
* from messages
where user_id_sender = 1
-- order by message_date DESC
) T where T.rowno = 1
Explanation: For each group of user_id_sender, it orders internally by message_date desc, and then adds row numbers, and we only want the first one (chronologically last). Then do the same for user_id_receiver, and union the results together to get 1 result set with all the desired rows. You can then add your own order by clause and additional where conditions at the end as required.
Of course, this only works for any 1 user_id at a time (replace =1 with #user_id).
To get a result from all user_id's at once, is a totally different query, so I hope this helps?
I'm stuck with a query which should be pretty simple but, for reasons unknown, my brain is not playing ball here ...
Table:
id(int) | strategy (varchar) | value (whatever)
1 "ABC" whatevs
2 "ABC" yeah
3 "DEF" hello
4 "DEF" kitty
5 "QQQ" hurrr
The query should select ALL rows grouped on strategy but only one row per strategy - the one with the higest id.
In the case above, it should return rows with id 2, 4 and 5
SELECT id, strategy , value
FROM (
SELECT id, strategy , value
,ROW_NUMBER() OVER (PARTITION BY strategy ORDER BY ID DESC) rn
FROM Table_Name
) Sub
WHERE rn = 1
Working SQL FIDDLE
You can use window function to get the solution you want. Fiddle here
with cte as
(
select
rank()over(partition by strategy order by id desc) as rnk,
id, strategy, value from myT
)
select id, strategy, value from
cte where rnk = 1;
Try this:
SELECT T2.id,T1.strategy,T1.value
FROM TableName T1
INNER JOIN
(SELECT MAX(id) as id,strategy
FROM TableName
GROUP BY strategy) T2
ON T1.id=T2.id
Result:
ID STRATEGY VALUE
2 ABC yeah
4 DEF kitty
5 QQQ hurrr
See result in SQL Fiddle.
SELECT id, strategy , value
FROM (
SELECT id, strategy , value
,MAX(id) OVER (PARTITION BY strategy) MaxId
FROM YourTable
) Sub
WHERE id=MaxId
You may try this one as well:
SELECT id, strategy, value FROM TableName WHERE id IN (
SELECT MAX(id) FROM TableName GROUP BY strategy
)
Bit depends on your data, you might get results faster with it as it does not do sorting, but by the other hand it uses IN, which can slow you down if there is many 'strategies'
I have a table with some number of records in it say the table is Student and it has a column named total_mark . Now I need to fetch the details of the student who is 7th largest total from the total_mark column . How to perform this operation in SQL SERVER 2008?
First, define what you mean by "7th". 7th in age? 7th in IQ? 7th in height? Whatever.
WITH
RankedStudents AS (
SELECT *, ROW_NUMBER() OVER ( ORDER BY <Whatever> ) AS RowNumber FROM <Schema>.<Object>
)
SELECT *
FROM RankedStudents
WHERE RowNumber = 7 ;
First select the top 7, then reverse the ordering and take just the first row:
SELECT TOP 1 * FROM (
SELECT TOP 7 *
FROM RankedStudents
ORDER BY total_mark desc) x
ORDER BY total_mark
try this
WITH CTE AS(
SELECT total_mark,RANK() OVER (ORDER BY total_mark DESC)AS RANKED FROM SN_DB)
SELECT DISTINCT * FROM CTE WHERE RANKED = 7
I am trying to have a running average column in the SELECT statement based on a column from the n previous rows in the same SELECT statement. The average I need is based on the n previous rows in the resultset.
Let me explain
Id Number Average
1 1 NULL
2 3 NULL
3 2 NULL
4 4 2 <----- Average of (1, 3, 2),Numbers from previous 3 rows
5 6 3 <----- Average of (3, 2, 4),Numbers from previous 3 rows
. . .
. . .
The first 3 rows of the Average column are null because there are no previous rows. The row 4 in the Average column shows the average of the Number column from the previous 3 rows.
I need some help trying to construct a SQL Select statement that will do this.
This should do it:
--Test Data
CREATE TABLE RowsToAverage
(
ID int NOT NULL,
Number int NOT NULL
)
INSERT RowsToAverage(ID, Number)
SELECT 1, 1
UNION ALL
SELECT 2, 3
UNION ALL
SELECT 3, 2
UNION ALL
SELECT 4, 4
UNION ALL
SELECT 5, 6
UNION ALL
SELECT 6, 8
UNION ALL
SELECT 7, 10
--The query
;WITH NumberedRows
AS
(
SELECT rta.*, row_number() OVER (ORDER BY rta.ID ASC) AS RowNumber
FROM RowsToAverage rta
)
SELECT nr.ID, nr.Number,
CASE
WHEN nr.RowNumber <=3 THEN NULL
ELSE ( SELECT avg(Number)
FROM NumberedRows
WHERE RowNumber < nr.RowNumber
AND RowNumber >= nr.RowNumber - 3
)
END AS MovingAverage
FROM NumberedRows nr
Assuming that the Id column is sequential, here's a simplified query for a table named "MyTable":
SELECT
b.Id,
b.Number,
(
SELECT
AVG(a.Number)
FROM
MyTable a
WHERE
a.id >= (b.Id - 3)
AND a.id < b.Id
AND b.Id > 3
) as Average
FROM
MyTable b;
Edit: I missed the point that it should average the three previous records...
For a general running average, I think something like this would work:
SELECT
id, number,
SUM(number) OVER (ORDER BY ID) /
ROW_NUMBER() OVER (ORDER BY ID) AS [RunningAverage]
FROM myTable
ORDER BY ID
A simple self join would seem to perform much better than a row referencing subquery
Generate 10k rows of test data:
drop table test10k
create table test10k (Id int, Number int, constraint test10k_cpk primary key clustered (id))
;WITH digits AS (
SELECT 0 as Number
UNION SELECT 1
UNION SELECT 2
UNION SELECT 3
UNION SELECT 4
UNION SELECT 5
UNION SELECT 6
UNION SELECT 7
UNION SELECT 8
UNION SELECT 9
)
,numbers as (
SELECT
(thousands.Number * 1000)
+ (hundreds.Number * 100)
+ (tens.Number * 10)
+ ones.Number AS Number
FROM digits AS ones
CROSS JOIN digits AS tens
CROSS JOIN digits AS hundreds
CROSS JOIN digits AS thousands
)
insert test10k (Id, Number)
select Number, Number
from numbers
I would pull the special case of the first 3 rows out of the main query, you can UNION ALL those back in if you really want it in the row set. Self join query:
;WITH NumberedRows
AS
(
SELECT rta.*, row_number() OVER (ORDER BY rta.ID ASC) AS RowNumber
FROM test10k rta
)
SELECT nr.ID, nr.Number,
avg(trailing.Number) as MovingAverage
FROM NumberedRows nr
join NumberedRows as trailing on trailing.RowNumber between nr.RowNumber-3 and nr.RowNumber-1
where nr.Number > 3
group by nr.id, nr.Number
On my machine this takes about 10 seconds, the subquery approach that Aaron Alton demonstrated takes about 45 seconds (after I changed it to reflect my test source table) :
;WITH NumberedRows
AS
(
SELECT rta.*, row_number() OVER (ORDER BY rta.ID ASC) AS RowNumber
FROM test10k rta
)
SELECT nr.ID, nr.Number,
CASE
WHEN nr.RowNumber <=3 THEN NULL
ELSE ( SELECT avg(Number)
FROM NumberedRows
WHERE RowNumber < nr.RowNumber
AND RowNumber >= nr.RowNumber - 3
)
END AS MovingAverage
FROM NumberedRows nr
If you do a SET STATISTICS PROFILE ON, you can see the self join has 10k executes on the table spool. The subquery has 10k executes on the filter, aggregate, and other steps.
Want to improve this post? Provide detailed answers to this question, including citations and an explanation of why your answer is correct. Answers without enough detail may be edited or deleted.
Check out some solutions here. I'm sure that you could adapt one of them easily enough.
If you want this to be truly performant, and arn't afraid to dig into a seldom-used area of SQL Server, you should look into writing a custom aggregate function. SQL Server 2005 and 2008 brought CLR integration to the table, including the ability to write user aggregate functions. A custom running total aggregate would be the most efficient way to calculate a running average like this, by far.
Alternatively you can denormalize and store precalculated running values. Described here:
http://sqlblog.com/blogs/alexander_kuznetsov/archive/2009/01/23/denormalizing-to-enforce-business-rules-running-totals.aspx
Performance of selects is as fast as it goes. Of course, modifications are slower.