Which of the following is the best method to implement select top n in Oracle?

The following article describes how to implement the select top n operation in Oracle. We use the following example to illustrate how to implement the select top n operation in Oracle, the following is a description of the specific content of the article.

1. implement select top n in Oracle

Since Oracle does not support the select top statement, order by and ROWNUM are often used in Oracle to query the select top n statement.

To put it simply, the method for implementing select top n in Oracle is as follows:

SELECT column name 1... column name n FROM

(SELECT column name 1... column name n FROM table name order by column name 1... column name n)

Where rownum <= N number of extracted Records)

 
 

  
  
ORDER BY ROWNUM ASC 
 
 

The following is a simple example.

The customer (id, name) Table has the following data:

ID NAME

01 first

02 Second

03 third

04 forth

05 th

06 sixth

07 seventh

08 eighth

09 ninth

10 tenth

11 last

The SQL statements of the first three customers are extracted by NAME as follows:

 
 

  
  
SELECT * FROM  
  
  
(SELECT * FROM CUSTOMER ORDER BY NAME)  
  
  
WHERE ROWNUM <= 3  
  
  
ORDER BY ROWNUM ASC  
 
 

Output result:

ID NAME

08 eighth

05 th

01 first

The above content describes how to implement the select top n method in Oracle, hoping to help you in this regard.