find every 5th record from table - sql

There are n record in a table ABC .
write a query to select every 5th record from the table.
for example there are 30 rows in a table.
so query should output 5th,10th,15th,20th, 25th and 30th record from the table.
I tried ROW_NUMBER OVER (ORDER BY id ) but getting msg :-
Message from SQL server IML (msg 156, level 15, state 2):
Incorrect syntax near the keyword 'OVER'.
I am using Sybase database.


You need to define order to get every 5th row. It can be for example PRIMARY KEY ID or something like this
select * from
(
select ABC.*, ROW_NUMBER() OVER (ORDER BY id) as RN from ABC
) t1
where RN % 5 = 0


This is not how SQL works. I'm not sure which column would give you what you want, but you aren't supposed to know or care about how the data is stored or what the ordering might be.
You need to figure out a WHERE clause that gives you what you want. Something depending on order is wrong.


try this
select rn, col_list from (select rownum rn, col_list from tab_name)
where rn=N;
where N is the row number you want.


Try this way.
Create temporary table with identity column.
select
id = identity(8),
column1,....
into #ABC
from ABC
Select with modulo:
select * from #ABC
where id % 5 = 0

Related

SQL query looping for each value in a list

New to SQL here - I am trying to get 1 row from a table matching to a particular criteria
Typically this would look like
SELECT TOP 1 *
FROM myTable
WHERE id = 'abc'
The output may look like
value id
--------------
1 abc
The table has many entries for an 'id', and I am trying to get one entry per 'id'. Now I have list of 'id's. How would I execute something like
SELECT TOP 1 *
FROM myTable
FOR EACH id
WHERE id IN ('abc', 'edf', 'fgh')
Expecting result like
value id
--------------
1 abc
10 edf
12 fgh
I do not know if it is some sort union or concat operation, but would like to learn. I am working on Azure SQL Server

The table has many entries for an 'id', and I am trying to get one entry per 'id'. Now I have list of 'id's.
A typical method is row_number():
select t.*
from (select t.*,
row_number() over (partition by id order by id) as seqnum
from mytable t
) t
where seqnum = 1;
Note: you can filter on particular ids, if you want. It is unclear if that is really required for your question.
If you happen to be using SQL Server (as select top suggests), you can use the more concise, but somewhat less performant:
select top (1) with ties t.*
from mytable t
order by row_number() over (order by id order by (select null));

Select nth row using where condition in oracle database [duplicate]

I'm interested in learning some (ideally) database agnostic ways of selecting the nth row from a database table. It would also be interesting to see how this can be achieved using the native functionality of the following databases:
SQL Server
MySQL
PostgreSQL
SQLite
Oracle
I am currently doing something like the following in SQL Server 2005, but I'd be interested in seeing other's more agnostic approaches:
WITH Ordered AS (
SELECT ROW_NUMBER() OVER (ORDER BY OrderID) AS RowNumber, OrderID, OrderDate
FROM Orders)
SELECT *
FROM Ordered
WHERE RowNumber = 1000000
Credit for the above SQL: Firoz Ansari's Weblog
Update: See Troels Arvin's answer regarding the SQL standard. Troels, have you got any links we can cite?

There are ways of doing this in optional parts of the standard, but a lot of databases support their own way of doing it.
A really good site that talks about this and other things is http://troels.arvin.dk/db/rdbms/#select-limit.
Basically, PostgreSQL and MySQL supports the non-standard:
SELECT...
LIMIT y OFFSET x
Oracle, DB2 and MSSQL supports the standard windowing functions:
SELECT * FROM (
SELECT
ROW_NUMBER() OVER (ORDER BY key ASC) AS rownumber,
columns
FROM tablename
) AS foo
WHERE rownumber <= n
(which I just copied from the site linked above since I never use those DBs)
Update: As of PostgreSQL 8.4 the standard windowing functions are supported, so expect the second example to work for PostgreSQL as well.
Update: SQLite added window functions support in version 3.25.0 on 2018-09-15 so both forms also work in SQLite.

PostgreSQL supports windowing functions as defined by the SQL standard, but they're awkward, so most people use (the non-standard) LIMIT / OFFSET:
SELECT
*
FROM
mytable
ORDER BY
somefield
LIMIT 1 OFFSET 20;
This example selects the 21st row. OFFSET 20 is telling Postgres to skip the first 20 records. If you don't specify an ORDER BY clause, there's no guarantee which record you will get back, which is rarely useful.

I'm not sure about any of the rest, but I know SQLite and MySQL don't have any "default" row ordering. In those two dialects, at least, the following snippet grabs the 15th entry from the_table, sorting by the date/time it was added:
SELECT *
FROM the_table
ORDER BY added DESC
LIMIT 1,15
(of course, you'd need to have an added DATETIME field, and set it to the date/time that entry was added...)

SQL 2005 and above has this feature built-in. Use the ROW_NUMBER() function. It is excellent for web-pages with a << Prev and Next >> style browsing:
Syntax:
SELECT
*
FROM
(
SELECT
ROW_NUMBER () OVER (ORDER BY MyColumnToOrderBy) AS RowNum,
*
FROM
Table_1
) sub
WHERE
RowNum = 23

I suspect this is wildly inefficient but is quite a simple approach, which worked on a small dataset that I tried it on.
select top 1 field
from table
where field in (select top 5 field from table order by field asc)
order by field desc
This would get the 5th item, change the second top number to get a different nth item
SQL server only (I think) but should work on older versions that do not support ROW_NUMBER().

Verify it on SQL Server:
Select top 10 * From emp
EXCEPT
Select top 9 * From emp
This will give you 10th ROW of emp table!

Contrary to what some of the answers claim, the SQL standard is not silent regarding this subject.
Since SQL:2003, you have been able to use "window functions" to skip rows and limit result sets.
And in SQL:2008, a slightly simpler approach had been added, using
OFFSET skip ROWS
FETCH FIRST n ROWS ONLY
Personally, I don't think that SQL:2008's addition was really needed, so if I were ISO, I would have kept it out of an already rather large standard.

1 small change: n-1 instead of n.
select *
from thetable
limit n-1, 1

SQL SERVER
Select n' th record from top
SELECT * FROM (
SELECT
ID, NAME, ROW_NUMBER() OVER(ORDER BY ID) AS ROW
FROM TABLE
) AS TMP
WHERE ROW = n
select n' th record from bottom
SELECT * FROM (
SELECT
ID, NAME, ROW_NUMBER() OVER(ORDER BY ID DESC) AS ROW
FROM TABLE
) AS TMP
WHERE ROW = n

When we used to work in MSSQL 2000, we did what we called the "triple-flip":
EDITED
DECLARE #InnerPageSize int
DECLARE #OuterPageSize int
DECLARE #Count int
SELECT #Count = COUNT(<column>) FROM <TABLE>
SET #InnerPageSize = #PageNum * #PageSize
SET #OuterPageSize = #Count - ((#PageNum - 1) * #PageSize)
IF (#OuterPageSize < 0)
SET #OuterPageSize = 0
ELSE IF (#OuterPageSize > #PageSize)
SET #OuterPageSize = #PageSize
DECLARE #sql NVARCHAR(8000)
SET #sql = 'SELECT * FROM
(
SELECT TOP ' + CAST(#OuterPageSize AS nvarchar(5)) + ' * FROM
(
SELECT TOP ' + CAST(#InnerPageSize AS nvarchar(5)) + ' * FROM <TABLE> ORDER BY <column> ASC
) AS t1 ORDER BY <column> DESC
) AS t2 ORDER BY <column> ASC'
PRINT #sql
EXECUTE sp_executesql #sql
It wasn't elegant, and it wasn't fast, but it worked.

In Oracle 12c, You may use OFFSET..FETCH..ROWS option with ORDER BY
For example, to get the 3rd record from top:
SELECT *
FROM sometable
ORDER BY column_name
OFFSET 2 ROWS FETCH NEXT 1 ROWS ONLY;

Here is a fast solution of your confusion.
SELECT * FROM table ORDER BY `id` DESC LIMIT N, 1
Here You may get Last row by Filling N=0, Second last by N=1, Fourth Last By Filling N=3 and so on.
This is very common question over the interview and this is Very simple ans of it.
Further If you want Amount, ID or some Numeric Sorting Order than u may go for CAST function in MySQL.
SELECT DISTINCT (`amount`)
FROM cart
ORDER BY CAST( `amount` AS SIGNED ) DESC
LIMIT 4 , 1
Here By filling N = 4 You will be able to get Fifth Last Record of Highest Amount from CART table. You can fit your field and table name and come up with solution.

ADD:
LIMIT n,1
That will limit the results to one result starting at result n.

Oracle:
select * from (select foo from bar order by foo) where ROWNUM = x

For example, if you want to select every 10th row in MSSQL, you can use;
SELECT * FROM (
SELECT
ROW_NUMBER() OVER (ORDER BY ColumnName1 ASC) AS rownumber, ColumnName1, ColumnName2
FROM TableName
) AS foo
WHERE rownumber % 10 = 0
Just take the MOD and change number 10 here any number you want.

For SQL Server, a generic way to go by row number is as such:
SET ROWCOUNT #row --#row = the row number you wish to work on.
For Example:
set rowcount 20 --sets row to 20th row
select meat, cheese from dbo.sandwich --select columns from table at 20th row
set rowcount 0 --sets rowcount back to all rows
This will return the 20th row's information. Be sure to put in the rowcount 0 afterward.

Here's a generic version of a sproc I recently wrote for Oracle that allows for dynamic paging/sorting - HTH
-- p_LowerBound = first row # in the returned set; if second page of 10 rows,
-- this would be 11 (-1 for unbounded/not set)
-- p_UpperBound = last row # in the returned set; if second page of 10 rows,
-- this would be 20 (-1 for unbounded/not set)
OPEN o_Cursor FOR
SELECT * FROM (
SELECT
Column1,
Column2
rownum AS rn
FROM
(
SELECT
tbl.Column1,
tbl.column2
FROM MyTable tbl
WHERE
tbl.Column1 = p_PKParam OR
tbl.Column1 = -1
ORDER BY
DECODE(p_sortOrder, 'A', DECODE(p_sortColumn, 1, Column1, 'X'),'X'),
DECODE(p_sortOrder, 'D', DECODE(p_sortColumn, 1, Column1, 'X'),'X') DESC,
DECODE(p_sortOrder, 'A', DECODE(p_sortColumn, 2, Column2, sysdate),sysdate),
DECODE(p_sortOrder, 'D', DECODE(p_sortColumn, 2, Column2, sysdate),sysdate) DESC
))
WHERE
(rn >= p_lowerBound OR p_lowerBound = -1) AND
(rn <= p_upperBound OR p_upperBound = -1);

But really, isn't all this really just parlor tricks for good database design in the first place? The few times I needed functionality like this it was for a simple one off query to make a quick report. For any real work, using tricks like these is inviting trouble. If selecting a particular row is needed then just have a column with a sequential value and be done with it.

Nothing fancy, no special functions, in case you use Caché like I do...
SELECT TOP 1 * FROM (
SELECT TOP n * FROM <table>
ORDER BY ID Desc
)
ORDER BY ID ASC
Given that you have an ID column or a datestamp column you can trust.

For SQL server, the following will return the first row from giving table.
declare #rowNumber int = 1;
select TOP(#rowNumber) * from [dbo].[someTable];
EXCEPT
select TOP(#rowNumber - 1) * from [dbo].[someTable];
You can loop through the values with something like this:
WHILE #constVar > 0
BEGIN
declare #rowNumber int = #consVar;
select TOP(#rowNumber) * from [dbo].[someTable];
EXCEPT
select TOP(#rowNumber - 1) * from [dbo].[someTable];
SET #constVar = #constVar - 1;
END;

LIMIT n,1 doesn't work in MS SQL Server. I think it's just about the only major database that doesn't support that syntax. To be fair, it isn't part of the SQL standard, although it is so widely supported that it should be. In everything except SQL server LIMIT works great. For SQL server, I haven't been able to find an elegant solution.

In Sybase SQL Anywhere:
SELECT TOP 1 START AT n * from table ORDER BY whatever
Don't forget the ORDER BY or it's meaningless.

T-SQL - Selecting N'th RecordNumber from a Table
select * from
(select row_number() over (order by Rand() desc) as Rno,* from TableName) T where T.Rno = RecordNumber
Where RecordNumber --> Record Number to Select
TableName --> To be Replaced with your Table Name
For e.g. to select 5 th record from a table Employee, your query should be
select * from
(select row_number() over (order by Rand() desc) as Rno,* from Employee) T where T.Rno = 5

SELECT
top 1 *
FROM
table_name
WHERE
column_name IN (
SELECT
top N column_name
FROM
TABLE
ORDER BY
column_name
)
ORDER BY
column_name DESC
I've written this query for finding Nth row.
Example with this query would be
SELECT
top 1 *
FROM
Employee
WHERE
emp_id IN (
SELECT
top 7 emp_id
FROM
Employee
ORDER BY
emp_id
)
ORDER BY
emp_id DESC

I'm a bit late to the party here but I have done this without the need for windowing or using
WHERE x IN (...)
SELECT TOP 1
--select the value needed from t1
[col2]
FROM
(
SELECT TOP 2 --the Nth row, alter this to taste
UE2.[col1],
UE2.[col2],
UE2.[date],
UE2.[time],
UE2.[UID]
FROM
[table1] AS UE2
WHERE
UE2.[col1] = ID --this is a subquery
AND
UE2.[col2] IS NOT NULL
ORDER BY
UE2.[date] DESC, UE2.[time] DESC --sorting by date and time newest first
) AS t1
ORDER BY t1.[date] ASC, t1.[time] ASC --this reverses the order of the sort in t1
It seems to work fairly fast although to be fair I only have around 500 rows of data
This works in MSSQL

SELECT * FROM emp a
WHERE n = (
SELECT COUNT( _rowid)
FROM emp b
WHERE a. _rowid >= b. _rowid
);

unbelievable that you can find a SQL engine executing this one ...
WITH sentence AS
(SELECT
stuff,
row = ROW_NUMBER() OVER (ORDER BY Id)
FROM
SentenceType
)
SELECT
sen.stuff
FROM sentence sen
WHERE sen.row = (ABS(CHECKSUM(NEWID())) % 100) + 1

select * from
(select * from ordered order by order_id limit 100) x order by
x.order_id desc limit 1;
First select top 100 rows by ordering in ascending and then select last row by ordering in descending and limit to 1. However this is a very expensive statement as it access the data twice.

It seems to me that, to be efficient, you need to 1) generate a random number between 0 and one less than the number of database records, and 2) be able to select the row at that position. Unfortunately, different databases have different random number generators and different ways to select a row at a position in a result set - usually you specify how many rows to skip and how many rows you want, but it's done differently for different databases. Here is something that works for me in SQLite:
select *
from Table
limit abs(random()) % (select count(*) from Words), 1;
It does depend on being able to use a subquery in the limit clause (which in SQLite is LIMIT <recs to skip>,<recs to take>) Selecting the number of records in a table should be particularly efficient, being part of the database's meta data, but that depends on the database's implementation. Also, I don't know if the query will actually build the result set before retrieving the Nth record, but I would hope that it doesn't need to. Note that I'm not specifying an "order by" clause. It might be better to "order by" something like the primary key, which will have an index - getting the Nth record from an index might be faster if the database can't get the Nth record from the database itself without building the result set.

Most suitable answer I have seen on this article for sql server
WITH myTableWithRows AS (
SELECT (ROW_NUMBER() OVER (ORDER BY myTable.SomeField)) as row,*
FROM myTable)
SELECT * FROM myTableWithRows WHERE row = 3

SQL query to fetch second last row or nth row from the table [duplicate]

I'm interested in learning some (ideally) database agnostic ways of selecting the nth row from a database table. It would also be interesting to see how this can be achieved using the native functionality of the following databases:
SQL Server
MySQL
PostgreSQL
SQLite
Oracle
I am currently doing something like the following in SQL Server 2005, but I'd be interested in seeing other's more agnostic approaches:
WITH Ordered AS (
SELECT ROW_NUMBER() OVER (ORDER BY OrderID) AS RowNumber, OrderID, OrderDate
FROM Orders)
SELECT *
FROM Ordered
WHERE RowNumber = 1000000
Credit for the above SQL: Firoz Ansari's Weblog
Update: See Troels Arvin's answer regarding the SQL standard. Troels, have you got any links we can cite?

There are ways of doing this in optional parts of the standard, but a lot of databases support their own way of doing it.
A really good site that talks about this and other things is http://troels.arvin.dk/db/rdbms/#select-limit.
Basically, PostgreSQL and MySQL supports the non-standard:
SELECT...
LIMIT y OFFSET x
Oracle, DB2 and MSSQL supports the standard windowing functions:
SELECT * FROM (
SELECT
ROW_NUMBER() OVER (ORDER BY key ASC) AS rownumber,
columns
FROM tablename
) AS foo
WHERE rownumber <= n
(which I just copied from the site linked above since I never use those DBs)
Update: As of PostgreSQL 8.4 the standard windowing functions are supported, so expect the second example to work for PostgreSQL as well.
Update: SQLite added window functions support in version 3.25.0 on 2018-09-15 so both forms also work in SQLite.

PostgreSQL supports windowing functions as defined by the SQL standard, but they're awkward, so most people use (the non-standard) LIMIT / OFFSET:
SELECT
*
FROM
mytable
ORDER BY
somefield
LIMIT 1 OFFSET 20;
This example selects the 21st row. OFFSET 20 is telling Postgres to skip the first 20 records. If you don't specify an ORDER BY clause, there's no guarantee which record you will get back, which is rarely useful.

I'm not sure about any of the rest, but I know SQLite and MySQL don't have any "default" row ordering. In those two dialects, at least, the following snippet grabs the 15th entry from the_table, sorting by the date/time it was added:
SELECT *
FROM the_table
ORDER BY added DESC
LIMIT 1,15
(of course, you'd need to have an added DATETIME field, and set it to the date/time that entry was added...)

SQL 2005 and above has this feature built-in. Use the ROW_NUMBER() function. It is excellent for web-pages with a << Prev and Next >> style browsing:
Syntax:
SELECT
*
FROM
(
SELECT
ROW_NUMBER () OVER (ORDER BY MyColumnToOrderBy) AS RowNum,
*
FROM
Table_1
) sub
WHERE
RowNum = 23

I suspect this is wildly inefficient but is quite a simple approach, which worked on a small dataset that I tried it on.
select top 1 field
from table
where field in (select top 5 field from table order by field asc)
order by field desc
This would get the 5th item, change the second top number to get a different nth item
SQL server only (I think) but should work on older versions that do not support ROW_NUMBER().

Verify it on SQL Server:
Select top 10 * From emp
EXCEPT
Select top 9 * From emp
This will give you 10th ROW of emp table!

Contrary to what some of the answers claim, the SQL standard is not silent regarding this subject.
Since SQL:2003, you have been able to use "window functions" to skip rows and limit result sets.
And in SQL:2008, a slightly simpler approach had been added, using
OFFSET skip ROWS
FETCH FIRST n ROWS ONLY
Personally, I don't think that SQL:2008's addition was really needed, so if I were ISO, I would have kept it out of an already rather large standard.

1 small change: n-1 instead of n.
select *
from thetable
limit n-1, 1

SQL SERVER
Select n' th record from top
SELECT * FROM (
SELECT
ID, NAME, ROW_NUMBER() OVER(ORDER BY ID) AS ROW
FROM TABLE
) AS TMP
WHERE ROW = n
select n' th record from bottom
SELECT * FROM (
SELECT
ID, NAME, ROW_NUMBER() OVER(ORDER BY ID DESC) AS ROW
FROM TABLE
) AS TMP
WHERE ROW = n

When we used to work in MSSQL 2000, we did what we called the "triple-flip":
EDITED
DECLARE #InnerPageSize int
DECLARE #OuterPageSize int
DECLARE #Count int
SELECT #Count = COUNT(<column>) FROM <TABLE>
SET #InnerPageSize = #PageNum * #PageSize
SET #OuterPageSize = #Count - ((#PageNum - 1) * #PageSize)
IF (#OuterPageSize < 0)
SET #OuterPageSize = 0
ELSE IF (#OuterPageSize > #PageSize)
SET #OuterPageSize = #PageSize
DECLARE #sql NVARCHAR(8000)
SET #sql = 'SELECT * FROM
(
SELECT TOP ' + CAST(#OuterPageSize AS nvarchar(5)) + ' * FROM
(
SELECT TOP ' + CAST(#InnerPageSize AS nvarchar(5)) + ' * FROM <TABLE> ORDER BY <column> ASC
) AS t1 ORDER BY <column> DESC
) AS t2 ORDER BY <column> ASC'
PRINT #sql
EXECUTE sp_executesql #sql
It wasn't elegant, and it wasn't fast, but it worked.

In Oracle 12c, You may use OFFSET..FETCH..ROWS option with ORDER BY
For example, to get the 3rd record from top:
SELECT *
FROM sometable
ORDER BY column_name
OFFSET 2 ROWS FETCH NEXT 1 ROWS ONLY;

Here is a fast solution of your confusion.
SELECT * FROM table ORDER BY `id` DESC LIMIT N, 1
Here You may get Last row by Filling N=0, Second last by N=1, Fourth Last By Filling N=3 and so on.
This is very common question over the interview and this is Very simple ans of it.
Further If you want Amount, ID or some Numeric Sorting Order than u may go for CAST function in MySQL.
SELECT DISTINCT (`amount`)
FROM cart
ORDER BY CAST( `amount` AS SIGNED ) DESC
LIMIT 4 , 1
Here By filling N = 4 You will be able to get Fifth Last Record of Highest Amount from CART table. You can fit your field and table name and come up with solution.

ADD:
LIMIT n,1
That will limit the results to one result starting at result n.

Oracle:
select * from (select foo from bar order by foo) where ROWNUM = x

For example, if you want to select every 10th row in MSSQL, you can use;
SELECT * FROM (
SELECT
ROW_NUMBER() OVER (ORDER BY ColumnName1 ASC) AS rownumber, ColumnName1, ColumnName2
FROM TableName
) AS foo
WHERE rownumber % 10 = 0
Just take the MOD and change number 10 here any number you want.

For SQL Server, a generic way to go by row number is as such:
SET ROWCOUNT #row --#row = the row number you wish to work on.
For Example:
set rowcount 20 --sets row to 20th row
select meat, cheese from dbo.sandwich --select columns from table at 20th row
set rowcount 0 --sets rowcount back to all rows
This will return the 20th row's information. Be sure to put in the rowcount 0 afterward.

Here's a generic version of a sproc I recently wrote for Oracle that allows for dynamic paging/sorting - HTH
-- p_LowerBound = first row # in the returned set; if second page of 10 rows,
-- this would be 11 (-1 for unbounded/not set)
-- p_UpperBound = last row # in the returned set; if second page of 10 rows,
-- this would be 20 (-1 for unbounded/not set)
OPEN o_Cursor FOR
SELECT * FROM (
SELECT
Column1,
Column2
rownum AS rn
FROM
(
SELECT
tbl.Column1,
tbl.column2
FROM MyTable tbl
WHERE
tbl.Column1 = p_PKParam OR
tbl.Column1 = -1
ORDER BY
DECODE(p_sortOrder, 'A', DECODE(p_sortColumn, 1, Column1, 'X'),'X'),
DECODE(p_sortOrder, 'D', DECODE(p_sortColumn, 1, Column1, 'X'),'X') DESC,
DECODE(p_sortOrder, 'A', DECODE(p_sortColumn, 2, Column2, sysdate),sysdate),
DECODE(p_sortOrder, 'D', DECODE(p_sortColumn, 2, Column2, sysdate),sysdate) DESC
))
WHERE
(rn >= p_lowerBound OR p_lowerBound = -1) AND
(rn <= p_upperBound OR p_upperBound = -1);

But really, isn't all this really just parlor tricks for good database design in the first place? The few times I needed functionality like this it was for a simple one off query to make a quick report. For any real work, using tricks like these is inviting trouble. If selecting a particular row is needed then just have a column with a sequential value and be done with it.

Nothing fancy, no special functions, in case you use Caché like I do...
SELECT TOP 1 * FROM (
SELECT TOP n * FROM <table>
ORDER BY ID Desc
)
ORDER BY ID ASC
Given that you have an ID column or a datestamp column you can trust.

For SQL server, the following will return the first row from giving table.
declare #rowNumber int = 1;
select TOP(#rowNumber) * from [dbo].[someTable];
EXCEPT
select TOP(#rowNumber - 1) * from [dbo].[someTable];
You can loop through the values with something like this:
WHILE #constVar > 0
BEGIN
declare #rowNumber int = #consVar;
select TOP(#rowNumber) * from [dbo].[someTable];
EXCEPT
select TOP(#rowNumber - 1) * from [dbo].[someTable];
SET #constVar = #constVar - 1;
END;

LIMIT n,1 doesn't work in MS SQL Server. I think it's just about the only major database that doesn't support that syntax. To be fair, it isn't part of the SQL standard, although it is so widely supported that it should be. In everything except SQL server LIMIT works great. For SQL server, I haven't been able to find an elegant solution.

In Sybase SQL Anywhere:
SELECT TOP 1 START AT n * from table ORDER BY whatever
Don't forget the ORDER BY or it's meaningless.

T-SQL - Selecting N'th RecordNumber from a Table
select * from
(select row_number() over (order by Rand() desc) as Rno,* from TableName) T where T.Rno = RecordNumber
Where RecordNumber --> Record Number to Select
TableName --> To be Replaced with your Table Name
For e.g. to select 5 th record from a table Employee, your query should be
select * from
(select row_number() over (order by Rand() desc) as Rno,* from Employee) T where T.Rno = 5

SELECT
top 1 *
FROM
table_name
WHERE
column_name IN (
SELECT
top N column_name
FROM
TABLE
ORDER BY
column_name
)
ORDER BY
column_name DESC
I've written this query for finding Nth row.
Example with this query would be
SELECT
top 1 *
FROM
Employee
WHERE
emp_id IN (
SELECT
top 7 emp_id
FROM
Employee
ORDER BY
emp_id
)
ORDER BY
emp_id DESC

I'm a bit late to the party here but I have done this without the need for windowing or using
WHERE x IN (...)
SELECT TOP 1
--select the value needed from t1
[col2]
FROM
(
SELECT TOP 2 --the Nth row, alter this to taste
UE2.[col1],
UE2.[col2],
UE2.[date],
UE2.[time],
UE2.[UID]
FROM
[table1] AS UE2
WHERE
UE2.[col1] = ID --this is a subquery
AND
UE2.[col2] IS NOT NULL
ORDER BY
UE2.[date] DESC, UE2.[time] DESC --sorting by date and time newest first
) AS t1
ORDER BY t1.[date] ASC, t1.[time] ASC --this reverses the order of the sort in t1
It seems to work fairly fast although to be fair I only have around 500 rows of data
This works in MSSQL

SELECT * FROM emp a
WHERE n = (
SELECT COUNT( _rowid)
FROM emp b
WHERE a. _rowid >= b. _rowid
);

unbelievable that you can find a SQL engine executing this one ...
WITH sentence AS
(SELECT
stuff,
row = ROW_NUMBER() OVER (ORDER BY Id)
FROM
SentenceType
)
SELECT
sen.stuff
FROM sentence sen
WHERE sen.row = (ABS(CHECKSUM(NEWID())) % 100) + 1

select * from
(select * from ordered order by order_id limit 100) x order by
x.order_id desc limit 1;
First select top 100 rows by ordering in ascending and then select last row by ordering in descending and limit to 1. However this is a very expensive statement as it access the data twice.

It seems to me that, to be efficient, you need to 1) generate a random number between 0 and one less than the number of database records, and 2) be able to select the row at that position. Unfortunately, different databases have different random number generators and different ways to select a row at a position in a result set - usually you specify how many rows to skip and how many rows you want, but it's done differently for different databases. Here is something that works for me in SQLite:
select *
from Table
limit abs(random()) % (select count(*) from Words), 1;
It does depend on being able to use a subquery in the limit clause (which in SQLite is LIMIT <recs to skip>,<recs to take>) Selecting the number of records in a table should be particularly efficient, being part of the database's meta data, but that depends on the database's implementation. Also, I don't know if the query will actually build the result set before retrieving the Nth record, but I would hope that it doesn't need to. Note that I'm not specifying an "order by" clause. It might be better to "order by" something like the primary key, which will have an index - getting the Nth record from an index might be faster if the database can't get the Nth record from the database itself without building the result set.

Most suitable answer I have seen on this article for sql server
WITH myTableWithRows AS (
SELECT (ROW_NUMBER() OVER (ORDER BY myTable.SomeField)) as row,*
FROM myTable)
SELECT * FROM myTableWithRows WHERE row = 3

Permuting values in SQL

Let's say I have a table with two columns:
id | value
----------
1 | 101
2 | 356
3 | 28
I need to randomly permute the value column so that each id is randomly assigned a new value from the existing set {101,356,28}. How could I do this in Oracle SQL?
It may sound odd but this is a real problem, just with more columns.

You can do this by using row_number() with a random number generator and then joining back to the original rows:
with cte as (
select id, value,
row_number() over (order by id) as i,
row_number() over (order by dbms_random.random) as rand_i
from table t
)
select cte.id, cte1.value
from cte join
cte cte1
on cte.i = cte.rand_i;
This guarantees a permutation (i.e. no original row has its value used twice).
EDIT:
By the way, if the original ids are sequential from 1 and have no gaps, you could just do:
select row_number() over (order by dbms.random) as id, value
from table t;

An Option : select * from x_table where id = round(dbms_random.value() * 3) + 1; [Here 3 is the number of rows in your random data table and I am assuming that id is incremental and unique?]
I'll think of other options.

I'm not sure whether this is the right task for SQL database. Maybe you should implement something like this:
Factoradic permutation - in PL/SQL and then return a cursor via PIPE ROW construct. Ordering by dbms.random might be slow for large data sets.

remove duplicate records with a criteria

I am using a script which requires only unique values. And I have a table which has duplicates like below, i need to keep only unique values (first occurrence) irrespective of what is present inside the brackets.
can I delete the records and keep the unique records using a single query?
Input table
ID Name
1 (Del)testing
2 (Del)test
3 (Delete)testing
4 (Delete)tester
5 (Del)tst
6 (Delete)tst
So the output tables should be something like
Input table
ID Name
1 (Del)testing
2 (Del)test
3 (Delete) tester
4 (Del)tst

SELECT DISTINCT * FROM FOO;
It depends how much data you have to retrieve, if you only have to change Delete -> Del you can try with REPLACE
http://technet.microsoft.com/en-us/library/ms186862.aspx
also grouping functions should help you
I don't think this would be easy query

Assumption: The name column always has all strings in the format given in the sample data.
Try this:
;with cte as
(select *, rank() over
(partition by substring(name, charindex(')',name)+1,len(name)+1 - charindex(')',name))
order by id) rn
from tbl
),
filtered_cte as
(select * from cte
where rn = 1
)
select rank() over (partition by getdate() order by id,getdate()) id , name
from filtered_cte
How this works:
The first CTE cte uses rank() to rank the occurrence of the string outside brackets in the name column.
The second CTE filtered_cte only returns the first row for each occurence of the specified string. In this step, we get the expected results, but not in the desired format.
In this step we partition by and order by the getdate() function. This function is chosen as a dummy to give us continuous values for the id column while using the rank function as we did in step 1.
Demo here.
Note that this solution will return filtered values, but not delete anything in the source table. If you wish, you can delete from the CTE created in step 1 to remove data from the source table.

First use this update to make them uniform
Update table set name = replace(Name, '(Del)' , '(Delete)')
then delete the repetitive names
Delete from table where id in
(Select id from (Select Row_Number() over(Partition by Name order by id) as rn,* from table) x
where rn > 1)

First create the input date table
CREATE TABLE test
(ID int,Name varchar(20));
INSERT INTO test
(`ID`, `Name`)
VALUES
(1, '(Del)testing'),
(2, '(Del)test'),
(3, '(Delete)testing'),
(4, '(Delete)tester'),
(5, '(Del)tst'),
(6, '(Delete)tst');
Select Query
select id, name
from (
select id, name ,
ROW_NUMBER() OVER(PARTITION BY substring(name,PATINDEX('%)%',name)+1,20) ORDER BY name) rn
from test ) t
where rn= 1
order by 1
SQL Fiddle Link
http://www.sqlfiddle.com/#!6/a02b0/34