I use SqlServer. I have a table with lots of columns the importants of which are:
· User_name
· Partition - Date in xxxx-xx-xx format
· Game - a string that works as an ID
· Credits - A number
· Bet - Another number
· Prize - Another number
· Num_Spins - Another number
I wrote a query to select of those the ones that interest me given a specific date.
Select distinct CONCAT(User_Name, DATALENGTH(User_Name)) as User_name, Partition, Game, Bet, Num_spins, Credits, Prize
from ***
where Partition>='2019-09-01' and Partition<'2019-11-17' and Bet>0 and credits is not null
and User_Name IN (Select distinct userName from *** where GeoIpCountryCode='ES')
I wish I could make that a view or something, but unfortunately I don't have the privileges to do so. Therefore, I do a subquery from it:
I want to find out of those rows, the ones whose numbers follow a certain math result: (Credits+Bet-Prize) > 100000 and num_spins>5
Select user_name, partition, count(Game) as difMachines
FROM
(
Select distinct CONCAT(User_Name, DATALENGTH(User_Name)) as User_name, Partition, Game, Bet, Num_spins, Credits, Prize
from ***
where Partition>='2019-09-01' and Partition<'2019-11-17' and Bet>0 and credits is not null
and User_Name IN (Select distinct userName from *** where GeoIpCountryCode='ES')
) as A
where
(Credits+Bet-Prize) > 100000 and num_spins>5
group by User_Name, Partition;
Now, I got all the information I need. I run the last query, to group_by date these results so I can analyze them:
Select datepart(week,Partition) as Week, count (distinct user_name) as Users
from (
Select user_name, partition, count(Game) as difMachines
FROM
(
Select distinct CONCAT(User_Name, DATALENGTH(User_Name)) as User_name, Partition, Game, Bet, Num_spins, Credits, Prize
from ***
where Partition>='2019-09-01' and Partition<'2019-11-17' and Bet>0 and credits is not null
and User_Name IN (Select distinct userName from *** where GeoIpCountryCode='ES')
) as A
where
(Credits+Bet-Prize) > 100000 and num_spins>5
group by User_Name, Partition
) as B
Where difMachines=1
group by datepart(week,Partition)
order by Week asc;
I know the query can be optimized, but that's not what troubles me. The problem is that when running this query, I obtain at week 36 17050 users. If I change this line (Credits+Bet-Prize) > 100000 and num_spins>5 for this one (Credits+Bet-Prize) > 100000 (so, I purely remove the num_spins>5 part), I get 16800 users instead.
To sum up, I get more results by being more restrictive in my query. That does not make sense to me. Someone please can help? Head me to the right direction or something?
Thank you
You are trying to get the count of result set with this filter diffmachine=1,isn't?. but if you remove the filter num_spins>5 then count will increase for diffmachine greater than 1.here i give an example like yours
Declare #t table
(
[user_name] varchar(5), [partition] date, Game varchar(10),num_spins int
)
insert into #t
select 'a','01nov19','g1',1
union all
select 'a','01nov19','g1',2
union all
select 'a','01nov19','g1',3
union all
select 'a','01nov19','g1',4
union all
select 'a','01nov19','g1',5
union all
select 'a','01nov19','g1',6
union all
select 'b','01nov19','g1',7
select * from
(
select [user_name],[partition],count(game) cnt
from #t
where num_spins>5
group by [user_name],[partition]
)a
where cnt=1
Related
So I'm trying to create a report that ranks a duplicate record, the idea behind this is that the customer wants to merge a whole lot of duplicate records that came about from a migration.
I need the ranking so that my report can show which record should be the "main" record, i.e. the record that will have missing data pulled into it.
The duplicate definition is pretty simple:
If the email addresses are the same then it is always a duplicate, if
the emails do not match, then the first name, surname, and mobile must
match.
The ranking will be based on a whole bunch of columns in the table, so:
email address isn't NULL = 50
phone number isn't NULL = 20
etc.. whichever gets the highest number in the duplicate group becomes the main record. This is where I am having issues, I can't seem to find a way to get an incremental number for each duplicate set. This is some of the code I have so far:
( I took out some of the rank columns in the temp table and CTE expression to shorten it )
DECLARE #tmp_Duplicates TABLE (
tmp_personID INT
, tmp_Firstname NVARCHAR(100)
, tmp_Surname NVARCHAR(100)
, tmp_HomeEmail NVARCHAR(300)
, tmp_MobileNumber NVARCHAR(100)
--- Ratings
, tmp_HomeEmail_Rating INT
--- Groupings
, tmp_GroupNumber INT
)
;WITH cteDupes AS
(
SELECT ROW_NUMBER() OVER(PARTITION BY personHomeEmail ORDER BY personID DESC) AS RND,
ROW_NUMBER() OVER(PARTITION BY personHomeEmail ORDER BY personId) AS RNA,
p.personID, p.PersonFirstName, p.PersonSurname, p.PersonHomeEMail
, personMobileTelephone
FROM tblCandidate c INNER JOIN tblPerson p ON c.candidateID = p.personID
)
INSERT INTO #tmp_Duplicates
SELECT PersonID, PersonFirstName, PersonSurname, PersonHomeEMail, personMobileTelephone
, 10, RND
FROM cteDupes
WHERE RNA + RND > 2
ORDER BY personID, PersonFirstName, PersonSurname
SELECT * FROM #tmp_Duplicates
This gives me the results I want, but the group number isn't showing how I need it:
What I need is for each group to be an incremental value:
I have a table in SQL, Employee_Details, having three columns, Name, Age and Salary. I came across this query to select the highest salary from the table which goes like this.
SELECT *
FROM Employee_Details e
WHERE 0 = (
SELECT count(DISTINCT Salary)
FROM Employee_Details
WHERE Salary > e.Salary
)
I have no idea about what the '0' signifies. Could anyone please give me an idea.
It's just a condition that says that the count from the Employee_Details table in the inner SELECT query must be 0 (no one can have a higher salary than the Employee selected in the outer SELECT)
The approach to do it this way seems a bit odd to me..... I would probably have used something like this:
SELECT (columns)
FROM dbo.Employee_Details e
WHERE e.Salary = (SELECT MAX(Salary) FROM dbo.Employee_Details)
which should produce the same result - only it seems a lot clearer to me what you're trying to achieve.
Get all from table Employee_details where count of salary is 0
Your query could be written as SELECT TOP 1 WITH TIES * FROM Employee_Details e ORDER BY Salary DESC (in T-SQL dialect). Condition in original query checks if the number of distinct values of Salary greater than Salary value in e is zero (i.e. there are no rows with greater Salary).
I want to select all records, but have the query only return a single record per Product Name. My table looks similar to:
SellId ProductName Comment
1 Cake dasd
2 Cake dasdasd
3 Bread dasdasdd
where the Product Name is not unique. I want the query to return a single record per ProductName with results like:
SellId ProductName Comment
1 Cake dasd
3 Bread dasdasdd
I have tried this query,
Select distict ProductName,Comment ,SellId from TBL#Sells
but it is returning multiple records with the same ProductName. My table is not realy as simple as this, this is just a sample. What is the solution? Is it clear?
Select ProductName,
min(Comment) , min(SellId) from TBL#Sells
group by ProductName
If y ou only want one record per productname, you ofcourse have to choose what value you want for the other fields.
If you aggregate (using group by) you can choose an aggregate function,
htat's a function that takes a list of values and return only one : here I have chosen MIN : that is the smallest walue for each field.
NOTE : comment and sellid can come from different records, since MIN is taken...
Othter aggregates you might find useful :
FIRST : first record encountered
LAST : last record encoutered
AVG : average
COUNT : number of records
first/last have the advantage that all fields are from the same record.
SELECT S.ProductName, S.Comment, S.SellId
FROM
Sells S
JOIN (SELECT MAX(SellId)
FROM Sells
GROUP BY ProductName) AS TopSell ON TopSell.SellId = S.SellId
This will get the latest comment as your selected comment assuming that SellId is an auto-incremented identity that goes up.
I know, you've got an answer already, I'd like to offer a way that was fastest in terms of performance for me, in a similar situation. I'm assuming that SellId is Primary Key and identity. You'd want an index on ProductName for best performance.
select
Sells.*
from
(
select
distinct ProductName
from
Sells
) x
join
Sells
on
Sells.ProductName = x.ProductName
and Sells.SellId =
(
select
top 1 s2.SellId
from
Sells s2
where
x.ProductName = s2.ProductName
Order By SellId
)
A slower method, (but still better than Group By and MIN on a long char column) is this:
select
*
from
(
select
*,ROW_NUMBER() over (PARTITION BY ProductName order by SellId) OccurenceId
from sells
) x
where
OccurenceId = 1
An advantage of this one is that it's much easier to read.
create table Sale
(
SaleId int not null
constraint PK_Sale primary key,
ProductName varchar(100) not null,
Comment varchar(100) not null
)
insert Sale
values
(1, 'Cake', 'dasd'),
(2, 'Cake', 'dasdasd'),
(3, 'Bread', 'dasdasdd')
-- Option #1 with over()
select *
from Sale
where SaleId in
(
select SaleId
from
(
select SaleId, row_number() over(partition by ProductName order by SaleId) RowNumber
from Sale
) tt
where RowNumber = 1
)
order by SaleId
-- Option #2
select *
from Sale
where SaleId in
(
select min(SaleId)
from Sale
group by ProductName
)
order by SaleId
drop table Sale
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.
I want to select the last 5 records from a table in SQL Server without arranging the table in ascending or descending order.
This is just about the most bizarre query I've ever written, but I'm pretty sure it gets the "last 5" rows from a table without ordering:
select *
from issues
where issueid not in (
select top (
(select count(*) from issues) - 5
) issueid
from issues
)
Note that this makes use of SQL Server 2005's ability to pass a value into the "top" clause - it doesn't work on SQL Server 2000.
Suppose you have an index on id, this will be lightning fast:
SELECT * FROM [MyTable] WHERE [id] > (SELECT MAX([id]) - 5 FROM [MyTable])
The way your question is phrased makes it sound like you think you have to physically resort the data in the table in order to get it back in the order you want. If so, this is not the case, the ORDER BY clause exists for this purpose. The physical order in which the records are stored remains unchanged when using ORDER BY. The records are sorted in memory (or in temporary disk space) before they are returned.
Note that the order that records get returned is not guaranteed without using an ORDER BY clause. So, while any of the the suggestions here may work, there is no reason to think they will continue to work, nor can you prove that they work in all cases with your current database. This is by design - I am assuming it is to give the database engine the freedom do as it will with the records in order to obtain best performance in the case where there is no explicit order specified.
Assuming you wanted the last 5 records sorted by the field Name in ascending order, you could do something like this, which should work in either SQL 2000 or 2005:
select Name
from (
select top 5 Name
from MyTable
order by Name desc
) a
order by Name asc
You need to count number of rows inside table ( say we have 12 rows )
then subtract 5 rows from them ( we are now in 7 )
select * where index_column > 7
select * from users
where user_id >
( (select COUNT(*) from users) - 5)
you can order them ASC or DESC
But when using this code
select TOP 5 from users order by user_id DESC
it will not be ordered easily.
select * from table limit 5 offset (select count(*) from table) - 5;
Without an order, this is impossible. What defines the "bottom"? The following will select 5 rows according to how they are stored in the database.
SELECT TOP 5 * FROM [TableName]
Well, the "last five rows" are actually the last five rows depending on your clustered index. Your clustered index, by definition, is the way that he rows are ordered. So you really can't get the "last five rows" without some order. You can, however, get the last five rows as it pertains to the clustered index.
SELECT TOP 5 * FROM MyTable
ORDER BY MyCLusteredIndexColumn1, MyCLusteredIndexColumnq, ..., MyCLusteredIndexColumnN DESC
Search 5 records from last records you can use this,
SELECT *
FROM Table Name
WHERE ID <= IDENT_CURRENT('Table Name')
AND ID >= IDENT_CURRENT('Table Name') - 5
If you know how many rows there will be in total you can use the ROW_NUMBER() function.
Here's an examble from MSDN (http://msdn.microsoft.com/en-us/library/ms186734.aspx)
USE AdventureWorks;
GO
WITH OrderedOrders AS
(
SELECT SalesOrderID, OrderDate,
ROW_NUMBER() OVER (ORDER BY OrderDate) AS 'RowNumber'
FROM Sales.SalesOrderHeader
)
SELECT *
FROM OrderedOrders
WHERE RowNumber BETWEEN 50 AND 60;
In SQL Server 2012 you can do this :
Declare #Count1 int ;
Select #Count1 = Count(*)
FROM [Log] AS L
SELECT
*
FROM [Log] AS L
ORDER BY L.id
OFFSET #Count - 5 ROWS
FETCH NEXT 5 ROWS ONLY;
Try this, if you don't have a primary key or identical column:
select [Stu_Id],[Student_Name] ,[City] ,[Registered],
RowNum = row_number() OVER (ORDER BY (SELECT 0))
from student
ORDER BY RowNum desc
You can retrieve them from memory.
So first you get the rows in a DataSet, and then get the last 5 out of the DataSet.
There is a handy trick that works in some databases for ordering in database order,
SELECT * FROM TableName ORDER BY true
Apparently, this can work in conjunction with any of the other suggestions posted here to leave the results in "order they came out of the database" order, which in some databases, is the order they were last modified in.
select *
from table
order by empno(primary key) desc
fetch first 5 rows only
Last 5 rows retrieve in mysql
This query working perfectly
SELECT * FROM (SELECT * FROM recharge ORDER BY sno DESC LIMIT 5)sub ORDER BY sno ASC
or
select sno from(select sno from recharge order by sno desc limit 5) as t where t.sno order by t.sno asc
When number of rows in table is less than 5 the answers of Matt Hamilton and msuvajac is Incorrect.
Because a TOP N rowcount value may not be negative.
A great example can be found Here.
i am using this code:
select * from tweets where placeID = '$placeID' and id > (
(select count(*) from tweets where placeID = '$placeID')-2)
In SQL Server, it does not seem possible without using ordering in the query.
This is what I have used.
SELECT *
FROM
(
SELECT TOP 5 *
FROM [MyTable]
ORDER BY Id DESC /*Primary Key*/
) AS T
ORDER BY T.Id ASC; /*Primary Key*/
DECLARE #MYVAR NVARCHAR(100)
DECLARE #step int
SET #step = 0;
DECLARE MYTESTCURSOR CURSOR
DYNAMIC
FOR
SELECT col FROM [dbo].[table]
OPEN MYTESTCURSOR
FETCH LAST FROM MYTESTCURSOR INTO #MYVAR
print #MYVAR;
WHILE #step < 10
BEGIN
FETCH PRIOR FROM MYTESTCURSOR INTO #MYVAR
print #MYVAR;
SET #step = #step + 1;
END
CLOSE MYTESTCURSOR
DEALLOCATE MYTESTCURSOR
Thanks to #Apps Tawale , Based on his answer, here's a bit of another (my) version,
To select last 5 records without an identity column,
select top 5 *,
RowNum = row_number() OVER (ORDER BY (SELECT 0))
from [dbo].[ViewEmployeeMaster]
ORDER BY RowNum desc
Nevertheless, it has an order by, but on RowNum :)
Note(1): The above query will reverse the order of what we get when we run the main select query.
So to maintain the order, we can slightly go like:
select *, RowNum2 = row_number() OVER (ORDER BY (SELECT 0))
from (
select top 5 *, RowNum = row_number() OVER (ORDER BY (SELECT 0))
from [dbo].[ViewEmployeeMaster]
ORDER BY RowNum desc
) as t1
order by RowNum2 desc
Note(2): Without an identity column, the query takes a bit of time in case of large data
Get the count of that table
select count(*) from TABLE
select top count * from TABLE where 'primary key row' NOT IN (select top (count-5) 'primary key row' from TABLE)
If you do not want to arrange the table in ascending or descending order. Use this.
select * from table limit 5 offset (select count(*) from table) - 5;