How do I do top 1 in Oracle? [duplicate]

How do I do the following?

select top 1 Fname from MyTbl 

In Oracle 11g?

9 Answers

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; 

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 

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.

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

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

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