This question already has answers here:
How do I limit the number of rows returned by an Oracle query after ordering?
(14 answers)
Closed 4 years ago.
I have to limit to 2 rows.
But can't do it for a SQL-Fetch.
select *
from employee;
You can use something like this:
select *
from
( select *
from emp
order by data desc )
where ROWNUM <= 2;
You can change the query as:
select *
from
top_n_test
order by
num
fetch first 3 rows only;
The select first n rows only selects the first n rows.
Well, the simplest way is to
select *
from employee
where rownum <= 2;
but the question is what exactly do you want to do with that.
Related
This question already has answers here:
Fetch the rows which have the Max value for a column for each distinct value of another column
(35 answers)
Closed 5 months ago.
I am trying to get the newest order for each phone number so I used in oracle
select * from (select * from orders where phonenum ='914780' order by order_date)
where rownum<=1
it works for one number only if I used it of several number it give me wrong results
as each number has several orders
Use window function for ordering phone number wise orders and then pick each phone number latest record.
Select *
from (
Select o.*,
row_number() over (partition by phonenum order by order_id desc) AS rowno
from order o
Where phonenum = '1233'
) t
Where t.rowno = 1;
N.B.: use table name and columns according to your DB objects.
This question already has answers here:
Oracle SELECT TOP 10 records [duplicate]
(6 answers)
How do I do top 1 in Oracle? [duplicate]
(9 answers)
How do I limit the number of rows returned by an Oracle query after ordering?
(14 answers)
Fetch the rows which have the Max value for a column for each distinct value of another column
(35 answers)
Closed 5 years ago.
I need to select from two tables,
RATING_TABLE
RATING_TYPE RATING_PRIORITY
TITAN 1
PLATINUM(+) 1
PLATINUM 2
DIAMOND(+) 3
DIAMOND 3
GOLD 4
SILVER 4
RATING_STORAGE
RATING AMOUNT
SILVER 200
GOLD 510
DIAMOND 850
PLATINUM(+) 980
TITAN 5000
I want to select the rating from RATING_STORAGE table based on RATING_PRIORITY from RATING_TABLE.
I want to select one row with lowest rating priority. If two rating priority are eqaul I want to choose the one with the lowest amount.
So I used the query,
select s.rating,s.amount
from RATING_TABLE r, RATING_STORAGE s
where r.rating_type= s.rating_type
and rownum=1
order by r.rating_priority asc , s.amount asc ;
I am getting correct output when sorting the result but rownum=1 fails to give the topmost row.
Thanks in Advance.
You need to select after sorting is done, in your case:
select *
from (select s.rating
,s.amount
from rating_table r
,rating_storage s
where r.rating_type = s.rating_type
and rownum = 1
order by r.rating_priority asc
,s.amount asc)
where rownum = 1;
This question already has answers here:
Oracle select most recent date record
(4 answers)
Closed 5 years ago.
I want to select the latest record from a table as based on a date field (crtn_dt). The query below does not work. Does anyone have an idea how it should be fixed?
select * from parcels
order by crtn_dt desc
where rownum = 1
You'd need to order data in the subquery and filter them in an outer query.
select *
from (
select *
from parcels
order by crtn_dt desc
)
where rownum = 1
order by clause is among last operations to perform.
What your query does, apart from being semantically incorrect, it returns one (thanks to rownum = 1 predicate) arbitrary row, and then applies order by clause to that one row.
So I have a simple table with 5 or so columns, one of which is a clob containing some JSON data.
I am running
SELECT * FROM BIG_TABLE
SELECT * FROM BIG_TABLE WHERE ROWNUM < 2
SELECT * FROM BIG_TABLE WHERE ROWNUM = 1
SELECT * FROM BIG_TABLE WHERE ID=x
I expect that any fractionally intelligent relational database would return the data immediately. We are not imposing order by/group by clauses, so why not return the data as and when you find it?
Of all the forms of SELECT statements above, only 4. returned in a sub-second manner. This is unexpected for 1-3 which are returning between 1 and 10 minutes before the query shows any responses in SQL Developer. SQL Developer has the standard SQL Array Fetch Size of 50 (JDBC Fetch size of 50 rows) so at a minimum, it is taking 1-10 minutes to return 50 rows from a simple table with no joins on a super high-performance RAC cluster backed by fancy 4-tiered EMC disk subsystem.
Explain plans show a table scan. Fine, but why should I wait 1-10 minutes for the results with rownum in the WHERE clause?
What is going on here?
OK - I found the issue. ROWNUM does not operate like I thought it did and in the code above it never stops the full table scan.
This is because:
RowNum is assigned during the predicate operation (where clause evaluation) and incremented afterwards, i.e.: your row makes it into the result set and then gets rownum assigned.
In order to filter by rownum you need to already have it exist, something like ...
SELECT * FROM (SELECT * FROM BIG_TABLE) WHERE ROWNUM < 1
In effect what this means is that there is no way to filter out the top 5 rows from a table without having first selected the entire table if no other filter criteria are involved.
I solved my problem like this...
SELECT * FROM (SELECT * FROM BIG_TABLE WHERE
DATE_COL BETWEEN :Date1 AND :Date2) WHERE ROWNUM < :x;
This question already has answers here:
How do I limit the number of rows returned by an Oracle query after ordering?
(14 answers)
Closed 9 years ago.
I have PHP + Oracle query like this :
$query_pag_data = "SELECT P.FORM_NO, P.MODEL_NO, P.PRODUCTION_STATUS, P.REMARKS, P.DATE_ADDED, P.TIME, P.QTY_PLAN, M.MODEL_NO, M.MODEL_NAME
FROM SEIAPPS_PRODUCTION_STATUS P, SEIAPPS_MODEL M
WHERE P.MODEL_NO = M.MODEL_NO ORDER BY P.DATE_ADDED DESC, P.TIME LIMIT $start, $per_page";
When I tried to search the problem, everyone said the problem is in LIMIT cant used in oracle.
How can I use LIMIT in ORACLE ?
Please advice.
Add a condition with where clause such as
"AND rownum <= 500"