I want to delete the duplicate records from the table So I used the CTE option but i am getting the below error message. What will be the cause? Am I did anything wrong? Upto select statement it works.
with Empcte as (
select *
, ROW_NUMBER() over (partition by ID ORDER BY ID) as RowNumber
from Empgender
)
SELECT *
FROM Empcte
delete from Empcte
where RowNumber > 1
Msg 208, Level 16, State 1, Line 8
Invalid object name 'Empcte'.
You can't use the same CTE for two different statements. (in this case first a SELECT and then a DELETE) You either have to re-create the CTE for the DELETE, or use a temp table or table variable instead of a CTE.
A CTE is a disposable view. It only persists for a single statement, and then disappears automatically. You can just avoid the SELECT statement:
WITH Empcte as (
SELECT id
,Count() as Rowcount
FROM Empgender
Group by id)
DELETE from Empgender where
Exists ( select 1 from Empgender as eg where Empcte.id = eg.id and Empcte.Rowcount >1 and );
Related
My Table, #MetaData looks like this
Table_Name Element Join_prefix
Incident hold_reason h
Incident impact i
Incident incident_state i
Incident notify n
Incident severity s
Incident state s
Change impact i
Change incident_state i
I want to update the join_prefix where it is the same, to the first 2 characters of the element, within the Table_Name. So the table looks like
Table_Name Element Join_prefix
Incident hold_reason h
Incident impact im
Incident incident_state in
Incident notify n
Incident severity se
Incident state st
Change impact im
Change incident_state in
I've been using the following sql but it updates all the rows
update #MetaData
set join_prefix=substring(element,1,2)
where exists(
select [Table_Name],[Join_prefix]
from #MetaData
group by [Table_Name],[Join_prefix]
having count(join_prefix)>1)
One method would be to use an updatable CTE. Within the CTE you can use a windowed COUNT to count how many rows have the same prefix, and then update those rows:
SELECT *
INTO dbo.YourTable
FROM (VALUES('Incident','hold_reason ',CONVERT(varchar(4),'h')),
('Incident','impact ',CONVERT(varchar(4),'i')),
('Incident','incident_state',CONVERT(varchar(4),'i')),
('Incident','notify ',CONVERT(varchar(4),'n')),
('Incident','severity ',CONVERT(varchar(4),'s')),
('Incident','state ',CONVERT(varchar(4),'s')),
('Change ','impact ',CONVERT(varchar(4),'i')),
('Change ','incident_state',CONVERT(varchar(4),'i')))V(Table_Name,Element,Join_prefix)
GO
WITH CTE AS(
SELECT Element,
Join_prefix,
COUNT(Join_prefix) OVER (PARTITION BY Join_prefix) AS C
FROM dbo.YourTable)
UPDATE CTE
SET Join_prefix = LEFT(Element,2)
WHERE C > 1;
GO
SELECT *
FROM dbo.YourTable;
GO
DROP TABLE dbo.YourTable;
Your subquery is not correlated to the outside, so it always returns true. You need a WHERE
Note that exists doesn't need to select anything, you can select 1.
Also count(*) and count(non_null_value) is the same
update m1
set join_prefix = substring(element, 1, 2)
from #MetaData m1
where exists (select 1
from #MetaData m2
where m2.join_prefix = m1.join_prefix
group by m2.Table_Name, m2.Join_prefix
having count(*) > 1
);
A better method would be an updatable CTE
with CTE as (
select *,
cnt = count(*) over (partition by m.Table_Name, m.join_prefix)
from #MetaData m
)
update CTE
set join_prefix = substring(element,1,2)
from #MetaData m1
where t.cnt > 1;
I'm using VS 2012 and SQL Server / SSIS.
I originally had a SQL task to check for duplicate values in a table:
SELECT COUNT(*) AS DupNI
FROM dbo.mytable
WHERE XMLFileID = ?
GROUP BY XMLFileID, NINumber
HAVING (COUNT(*) > 1);
The ? is because I am inserting a parameter value, and the result of the query is being assigned to a variable. It works fine if there is a duplicate.
When there are no duplicates, I get this message:
Single Row result set is specified, but no rows were returned
So, to get round this I now use an IF EXISTS, like the below:
IF EXISTS (SELECT COUNT(*) AS DupNI
FROM dbo.mytable
WHERE XMLFileID = ?
GROUP BY XMLFileID, NINumber
HAVING (COUNT(*) > 1))
SELECT COUNT(*) AS DupNI
FROM dbo.mytable
WHERE XMLFileID = ?
GROUP BY XMLFileID, NINumber
HAVING (COUNT(*) > 1)
ELSE
SELECT 0 AS DupNI;
However, now I get the error:
No value given for one or more required parameters.
It appears because I am wrapping the statement in the IF EXISTS, I can no longer inject the parameter values via the ?
Why is this? How do I get around this issue?
Your current query will return multiple rows if there are duplicates, one for each duplicate (XMLFileID, NINumber) pair. If you only want to return a value which indicates whether there are any duplicates in the table, you could use your EXISTS clause as an expression:
SELECT CASE WHEN EXISTS(
SELECT COUNT(*) AS DupNI
FROM dbo.mytable
WHERE XMLFileID = ?
GROUP BY XMLFileID, NINumber
HAVING (COUNT(*) > 1)
) THEN 1 ELSE 0 END AS [Duplicates Exist]
Demo on dbfiddle
I am using ROW_NUMBER() to find duplicates, encapsulated under CTEs. I am using ROW_NUMBER() because I also want to have column which shows how many duplicate rows are present in the table.
The below code gives only records greater than 1. That is row number 2 and 3. But how can I include row number 1 of duplicate records?
If I removed T>1, than output also contain records which does not have duplicate like records with Part "'0020R5',100".
DDL:
DROP TABLE #TEST
CREATE TABLE #TEST
(
PART VARCHAR(30),
ALTPART int
)
INSERT #TEST
SELECT '15-AB78',100 UNION ALL
SELECT '15-AB78',110 UNION ALL
SELECT '16-A9-1',100 UNION ALL
SELECT '16-A9-1',110 UNION ALL
SELECT '16-B97-2',100 UNION ALL
SELECT '16-B97-2',110 UNION ALL
SELECT '0020R5',100
Query:
WITH TEST(PART,ALTPART,T) AS
(
SELECT PART,ALTPART,ROW_NUMBER() OVER (PARTITION BY PART ORDER BY ALTPART ASC) AS T FROM #TEST
)
SELECT PART,ALTPART,T
FROM TEST
WHERE T>1
ORDER BY PART
GO
Current output:
'15-AB78',110,2
'16-A9-1',110,2
'16-B97-2',110,2
Expected Result:
'15-AB78',100,1
'15-AB78',110,2
'16-A9-1',100,1
'16-A9-1',110,2
'16-B97-2',100,1
'16-B97-2',110,2
You need to add another window function to count the number of duplicates in each group.
Something along these lines:
WITH TEST(PART,ALTPART,DuplicateNum, DuplicateCnt) AS
(
SELECT PART,ALTPART,
-- Number each duplicate
ROW_NUMBER() OVER (PARTITION BY PART ORDER BY ALTPART ASC) AS DuplicateNum,
-- Count duplicates
COUNT() OVER (PARTITION BY PART ) AS DuplicateCnt,
FROM #TEST
)
SELECT PART, ALTPART, DuplicateNum
FROM TEST
WHERE DuplicateCnt > 1
ORDER BY PART
I have a table that contains duplicates and I need to keep the max data and blow away the rest. Due to requirements I cannot change the date field format and I am getting a conversion error. Any ideas?
DELETE from MAIN_TBL
WHERE ID NOT IN
(
select * from
(SELECT MAX(updated_on)
FROM MAIN_TBL
GROUP BY widget_tag, ID) as TEMP
)
ERROR = Conversion failed when converting date and/or time from character string.
If you want to delete everything except newest rows per widget_tag you could use:
WITH cte AS (
SELECT *, ROW_NUMBER() OVER(PARITITION BY widget_tag ORDER BY updated_on DESC) rn
FROM MAIN_TBL
)
DELETE FROM cte WHERE rn <> 1;
You can use EXISTS:
DELETE t
from MAIN_TBL t
WHERE EXISTS (
SELECT 1 FROM MAIN_TBL
WHERE id = t.id and widget_tag = t.widget_tag and updated_on > t.updated_on
)
See the demo.
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;