How can I select the Nth row from a table in Oracle?
I tried
SELECT PRICE FROM AAA_PRICING WHERE ROWNUM = 2
but that didn't work. Please help!
Based on the classic answer:
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:127412348064
select *
from ( select a.*, rownum rnum
from ( YOUR_QUERY_GOES_HERE -- including the order by ) a
where rownum <= N_ROWS )
where rnum >= N_ROWS
/
Will not works with '=' (will works <2 or >2, but not equal)
so you can
SELECT Price from (SELECT PRICE, ROWNUM AS RN FROM AAA_PRICING) WHERE RN = 2
To address the reason for this:
The RowNum is a pseudo-column supplied by Oracle. It is generated while the SELECT-clause is being processed. Since the WHERE-clause is handled before the SELECT-clause, the RowNum does not have a proper value yet.
One can argue whether or not it makes sense to have Oracle throw an exception in situation, but because RowNum still is a pseudo-column it's still valid to have it there.
Note: Don't confuse this with RowId, which is an entire different story!
IMPORTANT EDIT:
Note that what I wrote about RowNum is only true for =, >, >=, IN () and maybe others. If you check for, e.g. RowNum < 10, you only get nine records!? I don't know why that is the case!
Select * From
(
Select Row_Number() OVER (Order by empno) rno, e.*
From scott.emp e
)
Where rno in (1, 3, 11)
SELECT PRICE
FROM (
SELECT PRICE,
ROWNUM rnum
FROM AAA_PRICING
ORDER BY PRICE ASC
)
WHERE rnum = 2
If you are on Oracle 12 or above, You can use the result offset and fetch clauses:
SELECT PRICE FROM AAA_PRICING
offset 1 rows fetch next 1 rows only
SELECT * FROM
(SELECT PRICE, ROWNUM AS RN FROM AAA_PRICING )
WHERE RN = 2;
select * from (Select Price, rownum as rn from(Select * from AAA_PRICING a order by a.Price))
where rn=2;
It will give you 2nd lowest price from the Price column. If you want simply 2nd row remove Order By condition.
ROWNUM is a pseudo column which generates unique pseudo values (equals to the number of records present in the SELECT statement o/p) during the execution of SELECT clause. When this pseudo column is specified with the WHERE clause it's value becomes 1 by default. So it behaves according to the comparison operator specified with it.
SELECT * FROM (
SELECT ROWNUM RN, E.*
FROM Emp E
)
WHERE RN = 10;
select *
From (select PRICE, DENSE_RANK() over(ORDER BY PRICE desc) as RNO
From AAA_PRICING
) t where RNO=2;
select a.*, rownum rnum
from ( select * from xyz_menu order by priority desc) a
where rownum < 5 ;
select * from xyz_menu order by priority desc
creating virtual table and also defining row number in virtual table
note: for oracle
Problem solved!
To select 2nd row in Oracle..
select SEN_NO,ITEM_NO from (select * from master_machine where
sen_no ='BGCWKKL23' and rownum <=2 order by
rownum desc,timestamp asc) where rownum <=1
Thank You!
Related
select tmp.id, tmp.portfolio,
ROW_NUMBER() OVER(order by tmp.id DESC) AS RowNum
from
(select r.portfolio, r.id
from research r
where r.created_by = 'Adam Cohen'
) as tmp
WHERE RowNum BETWEEN 5 AND 10;
I am not able refer the RowNum in the where condition, as it shows that Invalid column name 'RowNum'. Kindly help me to use the right syntax to get the result.
Edit - Changed Requirement
SELECT * FROM
(
select id, portfolio,
CASE WHEN l.posted_on IS NULL
THEN CONVERT(VARCHAR(40),l.created_on,120)
ELSE CONVERT(VARCHAR(40),l.posted_on,120)
END AS sort_by,
ROW_NUMBER() OVER(order by sort_by DESC) AS RowNum
from research
where created_by = 'Adam Cohen'
) x
WHERE x.RowNum BETWEEN 5 AND 10
I tried to include the Row_Number function like above but I got the sort_by as invalid column.
You'll need to wrap your projection in a derived table, although you can drop the inner tmp table:
SELECT * FROM
(
select id, portfolio,
ROW_NUMBER() OVER(order by id DESC) AS RowNum
from
research
where created_by = 'Adam Cohen'
) x
WHERE x.RowNum BETWEEN 5 AND 10
Edit
Note that if you don't actually need the pseudo row number in the final select, that since Sql 2012, in your 'page of data' scenario, that you will be able to use OFFSET FETCH apply the without the need for ROW_NUMBER() or derived tables at all:
select id, portfolio
from research
where created_by = 'Adam Cohen'
order by id desc
offset 5 rows fetch next 6 rows only;
Edit #2, Re new requirements
CASE WHEN l.posted_on IS NULL
THEN CONVERT(VARCHAR(40),l.created_on,120)
ELSE CONVERT(VARCHAR(40),l.posted_on,120)
END AS sort_by
Can be more concisely expressed as
CONVERT(VARCHAR(40), COALESCE(posted_on, created_on)) AS AS sort_by
However, if you still need original row number, you also use this projection in the ORDER BY of the windowing function (OVER), in order to DRY this up you will need the nested derived table. You can still use the SQL 2012 OFFSET / FETCH NEXT to paginate, however:
SELECT *,
ROW_NUMBER() OVER(order by sort_by DESC) AS RowNum
FROM
(
SELECT id, portfolio, CONVERT(VARCHAR(40), COALESCE(posted_on, created_on)) AS sort_by
from research
where created_by = 'Adam Cohen'
) y
ORDER BY id DESC
OFFSET 5 ROWS FETCH NEXT 6 ROWS ONLY;
You need to nest the ROW_NUMBER in the Derived Table:
select tmp.id, tmp.portfolio, tmp.RowNum
from
(select r.portfolio, r.id,
ROW_NUMBER() OVER(order by r.id DESC) AS RowNum
from research r
where r.created_by = 'Adam Cohen'
) as tmp
WHERE RowNum BETWEEN 5 AND 10;
My requirement is to get each client's latest order, and then get top 100 records.
I wrote one query as below to get latest orders for each client. Internal query works fine. But I don't know how to get first 100 based on the results.
SELECT * FROM (
SELECT id, client_id, ROW_NUMBER() OVER(PARTITION BY client_id ORDER BY create_time DESC) rn
FROM order
) WHERE rn=1
Any ideas? Thanks.
Assuming that create_time contains the time the order was created, and you want the 100 clients with the latest orders, you can:
add the create_time in your innermost query
order the results of your outer query by the create_time desc
add an outermost query that filters the first 100 rows using ROWNUM
Query:
SELECT * FROM (
SELECT * FROM (
SELECT
id,
client_id,
create_time,
ROW_NUMBER() OVER(PARTITION BY client_id ORDER BY create_time DESC) rn
FROM order
)
WHERE rn=1
ORDER BY create_time desc
) WHERE rownum <= 100
UPDATE for Oracle 12c
With release 12.1, Oracle introduced "real" Top-N queries. Using the new FETCH FIRST... syntax, you can also use:
SELECT * FROM (
SELECT
id,
client_id,
create_time,
ROW_NUMBER() OVER(PARTITION BY client_id ORDER BY create_time DESC) rn
FROM order
)
WHERE rn = 1
ORDER BY create_time desc
FETCH FIRST 100 ROWS ONLY)
you should use rownum in oracle to do what you seek
where rownum <= 100
see also those answers to help you
limit in oracle
select top in oracle
select top in oracle 2
As Moneer Kamal said, you can do that simply:
SELECT id, client_id FROM order
WHERE rownum <= 100
ORDER BY create_time DESC;
Notice that the ordering is done after getting the 100 row. This might be useful for who does not want ordering.
Update:
To use order by with rownum you have to write something like this:
SELECT * from (SELECT id, client_id FROM order ORDER BY create_time DESC) WHERE rownum <= 100;
First 10 customers inserted into db (table customers):
select * from customers where customer_id <=
(select min(customer_id)+10 from customers)
Last 10 customers inserted into db (table customers):
select * from customers where customer_id >=
(select max(customer_id)-10 from customers)
Hope this helps....
To select top n rows updated recently
SELECT *
FROM (
SELECT *
FROM table
ORDER BY UpdateDateTime DESC
)
WHERE ROWNUM < 101;
Try this:
SELECT *
FROM (SELECT * FROM (
SELECT
id,
client_id,
create_time,
ROW_NUMBER() OVER(PARTITION BY client_id ORDER BY create_time DESC) rn
FROM order
)
WHERE rn=1
ORDER BY create_time desc) alias_name
WHERE rownum <= 100
ORDER BY rownum;
Or TOP:
SELECT TOP 2 * FROM Customers; //But not supported in Oracle
NOTE: I suppose that your internal query is fine. Please share your output of this.
why below query is not giving results if I remove the < sign from query.Because even without < it must match with results?
Query used to get second max id value:
select min(id)
from(
select distinct id
from student
order by id desc
)
where rownum <=2
student id
1
2
3
4
Rownum has a special meaning in Oracle. It is increased with every row, but the optimizer knows that is increasing continuously and all consecutive rows must met the rownum condition. So if you specify rownum = 2 it will never occur since the first row is already rejected.
You can see this very nice if you do an explain plan on your query. It will show something like:
Plan for rownum <=:
COUNT STOPKEY
Plan for rownum =:
FILTER
A ROWNUM value is not assigned permanently to a row (this is a common misconception). A row in a table does not have a number; you cannot ask for row 2 or 3 from a table
click Here for more Info.
This is from the link provided:
Also confusing to many people is when a ROWNUM value is actually assigned. A ROWNUM value is assigned to a row after it passes the predicate phase of the query but before the query does any sorting or aggregation. Also, a ROWNUM value is incremented only after it is assigned, which is why the following query will never return a row:
select *
from t
where ROWNUM > 1;
Because ROWNUM > 1 is not true for the first row, ROWNUM does not advance to 2. Hence, no ROWNUM value ever gets to be greater than 1. Consider a query with this structure:
select ..., ROWNUM
from t
where <where clause>
group by <columns>
having <having clause>
order by <columns>;
I think this is the query you are looking for:
select id
from (select distinct id
from student
order by id desc
) t
where rownum <= 2;
Oracle processes the rownum before the order by, so you need a subquery to get the first two rows. The min() was forcing an aggregation that returned only one result, but before the rownum was applied.
If you actually want only the second value, you need an additional layer of subqueries:
select min(id)
from (select id
from (select distinct id
from student
order by id desc
) t
where rownum <= 2
) t;
However, I would do:
select id
from (select id, dense_rank() over (order by id) as seqnum
from student
) t
where seqnum = 2;
Order asc instead of desc
select id from student where rownum <=2 order by id asc;
Why not just use
select id
from ( select distinct id
, row_number() over (order by id desc) x
from student
)
where x = 2
Or even really bad. Getting the count and index :)
select id
from ( select id
, row_number() over (order by id desc) idx
, sum(1) over (order by null) cnt
from student
group
by id
)
where idx = cnt - 1 -- get the pre-last
Or
where idx = cnt - 2 -- get the 2nd-last
Or
where idx = 3 -- get the 3rd
Try this
SELECT *
FROM (
SELECT id, row_number() over (order by id asc) row_num
FROM student
) AS T
WHERE row_num = 2 -- or 3 ... n
ROW_NUMBER
I am using Oracle database and I have a table that have 1.9 billion rows of records. I want to get the rows of records ranging from 100,000,001 to 200,000,000. Can someone help me on this? Thank you in advance.
generally speaking you want a pagination query , which would be of the format:
select t.*
from (select t.*, rownum rn
from (select t.yourfields
from yourtab t
order by t.something)
where rownum <= end_rownum
) t
where rn >= offset;
or
select *
from (select t.yourfields, row_number() over (order by t.something) rn
from yourtab t)
where rn between start_rownum and end_rownum;
if you mean those ranges are rownum then here is simple the query
select * from (select e.*,rownum test from hr.employees e) where test>5 and test <50;
How do I retrieve the second highest value from a table?
select max(val) from table where val < (select max(val) form table)
In MySQL you could for instance use LIMIT 1, 1:
SELECT col FROM tbl ORDER BY col DESC LIMIT 1, 1
See the MySQL reference manual: SELECT Syntax).
The LIMIT clause can be used to constrain the number of rows returned by the SELECT statement. LIMIT takes one or two numeric arguments, which must both be nonnegative integer constants (except when using prepared statements).
With two arguments, the first argument specifies the offset of the first row to return, and the second specifies the maximum number of rows to return. The offset of the initial row is 0 (not 1):
SELECT * FROM tbl LIMIT 5,10; # Retrieve rows 6-15
select top 2 field_name from table_name order by field_name desc limit 1
SELECT E.lastname, E.salary FROM employees E
WHERE 2 = (SELECT COUNT(*) FROM employess E2
WHERE E2.salary > E.salary)
Taken from here
This works in almost all Dbs
Select Top 1 sq.ColumnToSelect
From
(Select Top 2 ColumnToSelect
From MyTable
Order by ColumnToSelect Desc
)sq
Order by sq.ColumnToSelect asc
Cool, this is almost like Code Golf.
Microsoft SQL Server 2005 and higher:
SELECT *
FROM (
SELECT
*,
row_number() OVER (ORDER BY var DESC) AS ranking
FROM table
) AS q
WHERE ranking = 2
Try this
SELECT * FROM
(SELECT empno, deptno, sal,
DENSE_RANK() OVER (PARTITION BY deptno ORDER BY sal DESC NULLS LAST) DENSE_RANK
FROM emp)
WHERE DENSE_RANK = 2;
This works in both Oracle and SQL Server.
Try this
SELECT TOP 1 Column FROM Table WHERE Column < (SELECT MAX(Column) FROM Table)
ORDER BY Column DESC
SELECT TOP 1 Column FROM (SELECT TOP <n> Column FROM Table ORDER BY Column DESC)
ORDER BY ASC
change the n to get the value of any position
Maybe:
SELECT * FROM table ORDER BY value DESC LIMIT 1, 1
one solution would be like this:
SELECT var FROM table ORDER BY var DESC LIMIT 1,1