Are there any functions in MySQL like dense_rank() and row_number() like Oracle?

问题

Are there any functions in MySQL like dense_rank() and row_number() like those provided by Oracle and other DBMS?

I want to generate an id within the query, but in MySQL these functions are not there. Is there an alternative?

回答1:

Mysql doesn't have them, but you can simulate row_number() with the following expression that uses a user defined variable:

(@row := ifnull(@row, 0) + 1)

like this:

select *, (@row := ifnull(@row, 0) + 1) row_number
from mytable
order by id

but if you're reusing the session, @row will still be set, so you'll need to reset it like this instead:

set @row := 0;
select *, (@row := @row + 1) row_number
from mytable
order by 1;

See SQLFiddle.

dense_rank() is possible but a train wreck; I advise handling that requirement in the app layer.

回答2:

We have now..

select ename, sal, dense_rank() over (order by sal desc)rnk
from emp2 e
order by rnk;

回答3:

In MySql you dont have dense_rank() or row_number() like the one in Oracle.

But you can create the same functionality through SQL query:

Here is an article doing the same:

dense_rank()

row_number()

回答4:

MySQL doesn't support these functions, but you can mimic them yourself. Shamelessly link to my solution to ROW_NUMBER, RANK and DENSE_RANK functions in MySQL

回答5:

DENSE_RANK() function is available in MySQL version 8.0. So if you're using MySQL version 8.0 you can run this command,

SELECT name, DENSE_RANK() OVER ( ORDER BY value ) my_rank FROM table_name;

回答6:

MySQL version 8 now has ROW_NUMBER. Documentation

EXAMPLE:

SELECT 
    ROW_NUMBER() OVER (ORDER BY s.Id) AS 'row_num', 
    s.product,
    s.title
FROM supplies AS S

来源：https://stackoverflow.com/questions/32494950/are-there-any-functions-in-mysql-like-dense-rank-and-row-number-like-oracle

标签

mysql

database

row-number