Related
Looking at :
;WITH cte AS(
SELECT 1 AS x UNION
SELECT 2 AS x UNION
SELECT 3 AS x
)
I can create permutation table for all 3 values :
SELECT T1.x , y=T2.x , z=t3.x
FROM cte T1
JOIN cte T2
ON T1.x != T2.x
JOIN cte T3
ON T2.x != T3.x AND T1.x != T3.x
This uses the power of SQL's cartesian product plus eliminating equal values.
OK.
But is it possible to enhance this recursive pseudo CTE :
;WITH cte AS(
SELECT 1 AS x , 2 AS y , 3 AS z
UNION ALL
...
)
SELECT * FROM cte
So that it will yield same result as :
NB there are other solutions in SO that uses recursive CTE , but it is not spread to columns , but string representation of the permutations
I tried to do the lot in a CTE.
However trying to "redefine" a rowset dynamically is a little tricky. While the task is relatively easy using dynamic SQL doing it without poses some issues.
While this answer may not be the most efficient or straight forward, or even correct in the sense that it's not all CTE it may give others a basis to work from.
To best understand my approach read the comments, but it might be worthwhile looking at each CTE expression in turn with by altering the bit of code below in the main block, with commenting out the section below it.
SELECT * FROM <CTE NAME>
Good luck.
IF OBJECT_ID('tempdb..#cteSchema') IS NOT NULL
DROP Table #cteSchema
GO
-- BASE CTE
;WITH cte AS( SELECT 1 AS x, 2 AS y, 3 AS z),
-- So we know what columns we have from the CTE we extract it to XML
Xml_Schema AS ( SELECT CONVERT(XML,(SELECT * FROM cte FOR XML PATH(''))) AS MySchema ),
-- Next we need to get a list of the columns from the CTE, by querying the XML, getting the values and assigning a num to the column
MyColumns AS (SELECT D.ROWS.value('fn:local-name(.)','SYSNAME') AS ColumnName,
D.ROWS.value('.','SYSNAME') as Value,
ROW_NUMBER() OVER (ORDER BY D.ROWS.value('fn:local-name(.)','SYSNAME')) AS Num
FROM Xml_Schema
CROSS APPLY Xml_Schema.MySchema.nodes('/*') AS D(ROWS) ),
-- How many columns we have in the CTE, used a coupld of times below
ColumnStats AS (SELECT MAX(NUM) AS ColumnCount FROM MyColumns),
-- create a cartesian product of the column names and values, so now we get each column with it's possible values,
-- so {x=1, x =2, x=3, y=1, y=2, y=3, z=1, z=2, z=3} -- you get the idea.
PossibleValues AS (SELECT MyC.ColumnName, MyC.Num AS ColumnNum, MyColumns.Value, MyColumns.Num,
ROW_NUMBER() OVER (ORDER BY MyC.ColumnName, MyColumns.Value, MyColumns.Num ) AS ID
FROM MyColumns
CROSS APPLY MyColumns MyC
),
-- Now we have the possibly values of each "column" we now have to concat the values together using this recursive CTE.
AllRawXmlRows AS (SELECT CONVERT(VARCHAR(MAX),'<'+ISNULL((SELECT ColumnName FROM MyColumns WHERE MyColumns.Num = 1),'')+'>'+Value) as ConcatedValue, Value,ID, Counterer = 1 FROM PossibleValues
UNION ALL
SELECT CONVERT(VARCHAR(MAX),CONVERT(VARCHAR(MAX), AllRawXmlRows.ConcatedValue)+'</'+(SELECT ColumnName FROM MyColumns WHERE MyColumns.Num = Counterer)+'><'+(SELECT ColumnName FROM MyColumns WHERE MyColumns.Num = Counterer+1)+'>'+CONVERT(VARCHAR(MAX),PossibleValues.Value)) AS ConcatedValue, PossibleValues.Value, PossibleValues.ID,
Counterer = Counterer+1
FROM AllRawXmlRows
INNER JOIN PossibleValues ON AllRawXmlRows.ConcatedValue NOT LIKE '%'+PossibleValues.Value+'%' -- I hate this, there has to be a better way of making sure we don't duplicate values....
AND AllRawXmlRows.ID <> PossibleValues.ID
AND Counterer < (SELECT ColumnStats.ColumnCount FROM ColumnStats)
),
-- The above made a list but was missing the final closing XML element. so we add it.
-- we also restict the list to the items that contain all columns, the section above builds it up over many columns
XmlRows AS (SELECT DISTINCT
ConcatedValue +'</'+(SELECT ColumnName FROM MyColumns WHERE MyColumns.Num = Counterer)+'>'
AS ConcatedValue
FROM AllRawXmlRows WHERE Counterer = (SELECT ColumnStats.ColumnCount FROM ColumnStats)
),
-- Wrap the output in row and table tags to create the final XML
FinalXML AS (SELECT (SELECT CONVERT(XML,(SELECT CONVERT(XML,ConcatedValue) FROM XmlRows FOR XML PATH('row'))) FOR XML PATH('table') )as XMLData),
-- Prepare a CTE that represents the structure of the original CTE with
DataTable AS (SELECT cte.*, XmlData
FROM FinalXML, cte)
--SELECT * FROM <CTE NAME>
-- GETS destination columns with XML data.
SELECT *
INTO #cteSchema
FROM DataTable
DECLARE #XML VARCHAR(MAX) ='';
SELECT #Xml = XMLData FROM #cteSchema --Extract XML Data from the
ALTER TABLE #cteSchema DROP Column XMLData -- Removes the superflous column
DECLARE #h INT
EXECUTE sp_xml_preparedocument #h OUTPUT, #XML
SELECT *
FROM OPENXML(#h, '/table/row', 2)
WITH #cteSchema -- just use the #cteSchema to define the structure of the xml that has been constructed
EXECUTE sp_xml_removedocument #h
How about translating 1,2,3 into a column, which will look exactly like the example you started from, and use the same approach ?
;WITH origin (x,y,z) AS (
SELECT 1,2,3
), translated (x) AS (
SELECT col
FROM origin
UNPIVOT ( col FOR cols IN (x,y,z)) AS up
)
SELECT T1.x , y=T2.x , z=t3.x
FROM translated T1
JOIN translated T2
ON T1.x != T2.x
JOIN translated T3
ON T2.x != T3.x AND T1.x != T3.x
ORDER BY 1,2,3
If I understood correctly the request, this might just do the trick.
And to run it on more columns, just need to add them origin cte definition + unpivot column list.
Now, i dont know how you pass your 1 - n values for it to be dynamic, but if you tell me, i could try edit the script to be dynamic too.
I have a table let's say it has four columns
Id, Name, Cell_no, Cat_id.
I need to return all columns whose count of Cat_id is greater than 1.
The group should be done on Cell_no and Name.
What i have done so far..
select Cell_no, COUNT(Cat_id)
from TableName
group by Cell_Number
having COUNT(Cat_id) > 1
But what i need is some thing like this.
select *
from TableName
group by Cell_Number
having COUNT(Cat_id) > 1
Pratik's answer is good but rather than using the IN operator (which only works for single values) you will need to JOIN back to the result set like this
SELECT t.*
FROM tableName t
INNER JOIN
(SELECT Cell_no, Name
FROM TableName
GROUP BY Cell_no , Name
HAVING COUNT(Cat_id) > 1) filter
ON t.Cell_no = filter.Cell_no AND t.Name = filter.Name
you just need to modify your query like below --
select * from tableName where (Cell_no, Name) in (
select Cell_no, Name from TableName
Group by Cell_no , Name
having COUNT(Cat_id) > 1
)
as asked in question you want to group by Cell_no and Name.. if so you need to change your query for group by columns and select part also.. as I have mentioned
This version requires only one pass over the data:
SELECT *
FROM (SELECT a.*
,COUNT(cat_id) OVER (PARTITION BY cell_no)
AS count_cat_id_not_null
FROM TableName a)
WHERE count_cat_id_not_null > 1;
Is it possible to access a temporary column that was defined in a query for a Common Table Expression? Say I have
select * from myTable
;with cte as
(
select
*, Salary * 4 as FourTimesSalary
from
Employees
where
Name = #name
and ID >= 100
)
Is there a way to use the temporary column FourTimesSalary when querying cte like so?
select top 2 *
from cte
order by FourTimesSalary, Name
TIA.
Yes you can do that. Example:
with temp as
(
select 1 as id, 2*4 as val
UNION
select 2 as id, 3*4 as val
)
SELECT * FROM temp ORDER BY VAL desc
Your example looks fine, did you get an error when you tried that or something?
I have a SQL Server 2008 query
SELECT TOP 10 *
FROM T
WHERE ...
ORDER BY ...
I'd like to get also the total number of the rows. The obious way is to make a second query
SELECT COUNT(*)
FROM T
WHERE ...
ORDER BY ...
Is there an efficient method?
Thanks
Do you want a second query?
SELECT TOP 10
*, foo.bar
FROM
T
CROSS JOIN
(SELECT COUNT(*) AS bar FROM T WHERE ...) foo
WHERE
...
ORDER BY
...
OR
DECLARE #bar int
SELECT #bar = COUNT(*) AS bar FROM T WHERE ...
SELECT TOP 10
*, #bar
FROM
T
CROSS JOIN
(SELECT COUNT(*) AS bar FROM T WHERE ...) foo
WHERE
...
ORDER BY
...
Or (Edit: using WITH)
WITH cTotal AS
(
SELECT COUNT(*) AS bar FROM T WHERE ...)
)
SELECT TOP 10
*, cTotal .bar
FROM
T
WHERE
...
ORDER BY
...
What is in this answer seems to work:
https://stackoverflow.com/a/19125458/16241
Basically you do a:
SELECT top 100 YourColumns, TotalCount = Count(*) Over()
From YourTable
Where SomeValue = 32
TotalCount will have the total number of rows. It is listed on each row though.
When I tested this the query plan showed the table only being hit once.
Remove the ORDER BY clause from the 2nd query as well.
No.
SQL Server doesn't keep COUNT(*) in metadata like MyISAM, it calculates it every time.
UPDATE: If you need an estimate, you can use statistics metadata:
SELECT rows
FROM dbo.sysindexes
WHERE name = #primary_key,
where #primary_key is your table's primary key name.
This will return the COUNT(*) from last statistics update.
SELECT TOP (2) *,
(SELECT COUNT(*) AS Expr1 FROM T) AS C
FROM T
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;