This question already has answers here: How do I limit the number of rows returned by an Oracle query after ordering? (14 answers) Closed 6 months ago.
How do I do the following?
select top 1 Fname from MyTbl
In Oracle 11g?
If you want just a first selected row, you can:
select fname from MyTbl where rownum = 1
You can also use analytic functions to order and take the top x:
select max(fname) over (rank() order by some_factor) from MyTbl
SELECT *
FROM (SELECT * FROM MyTbl ORDER BY Fname )
WHERE ROWNUM = 1;
top X
one can change it to WHERE ROWNUM <= X
With Oracle 12c (June 2013), you are able to use it like the following.
SELECT * FROM MYTABLE
--ORDER BY COLUMNNAME -OPTIONAL
OFFSET 0 ROWS FETCH NEXT 1 ROWS ONLY
OFFSET 0 ROWS
apparently is not necessary, you can use FETCH NEXT 1 ROWS ONLY
or even FETCH FIRST ROW ONLY
, the order by is important or it will be equivalent to just using a WHERE rownum = 1
. I've even tried it in an OUTER APPLY instruction and it worked like Ms-SQL's TOP function there.
TIES
. Refer this for the cases when ties occur for version 12c +
and 12c -
You could use ROW_NUMBER()
with a ORDER BY
clause in sub-query and use this column in replacement of TOP N
. This can be explained step-by-step.
See the below table which have two columns NAME
and DT_CREATED
.
https://i.stack.imgur.com/a8AS1.jpg
If you need to take only the first two dates irrespective of NAME
, you could use the below query. The logic has been written inside query
-- The number of records can be specified in WHERE clause
SELECT RNO,NAME,DT_CREATED
FROM
(
-- Generates numbers in a column in sequence in the order of date
SELECT ROW_NUMBER() OVER (ORDER BY DT_CREATED) AS RNO,
NAME,DT_CREATED
FROM DEMOTOP
)TAB
WHERE RNO<3;
RESULT
https://i.stack.imgur.com/f7Yfl.jpg
In some situations, we need to select TOP N
results respective to each NAME
. In such case we can use PARTITION BY
with an ORDER BY
clause in sub-query. Refer the below query.
-- The number of records can be specified in WHERE clause
SELECT RNO,NAME,DT_CREATED
FROM
(
--Generates numbers in a column in sequence in the order of date for each NAME
SELECT ROW_NUMBER() OVER (PARTITION BY NAME ORDER BY DT_CREATED) AS RNO,
NAME,DT_CREATED
FROM DEMOTOP
)TAB
WHERE RNO<3;
RESULT
https://i.stack.imgur.com/o203n.jpg
with (select ... ) as
clause) does not change anything to this problem, CTE just aims in reading and supporting queries. Right? @Sarath Avanavu
select * from (
select FName from MyTbl
)
where rownum <= 1;
You can do something like
SELECT *
FROM (SELECT Fname FROM MyTbl ORDER BY Fname )
WHERE rownum = 1;
You could also use the analytic functions RANK and/or DENSE_RANK, but ROWNUM is probably the easiest.
Use:
SELECT x.*
FROM (SELECT fname
FROM MyTbl) x
WHERE ROWNUM = 1
If using Oracle9i+, you could look at using analytic functions like ROW_NUMBER() but they won't perform as well as ROWNUM.
To select the first row from a table and to select one row from a table are two different tasks and need a different query. There are many possible ways to do so. Four of them are:
First
select max(Fname) from MyTbl;
Second
select min(Fname) from MyTbl;
Third
select Fname from MyTbl where rownum = 1;
Fourth
select max(Fname) from MyTbl where rowid=(select max(rowid) from MyTbl)
I had the same issue, and I can fix this with this solution:
select a.*, rownum
from (select Fname from MyTbl order by Fname DESC) a
where
rownum = 1
You can order your result before to have the first value on top.
Good luck
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