How to enumerate returned rows in SQL?

问题:

I was wondering if it would be possible to enumerate returned rows. Not according to any column content but just yielding a sequential integer index. E.g.

select ?, count(*) as usercount from users group by age

would return something along the lines:

1    12
2    78
3     4
4    42

it is for https://data.stackexchange.com/

回答1:

try:

SELECT
    ROW_NUMBER() OVER(ORDER BY age) AS RowNumber
        ,count(*) as usercount 
    from users 
    group by age

回答2:

If it's Oracle, use rownum.

SELECT SOMETABLE.*, ROWNUM RN
FROM SOMETABLE
WHERE SOMETABLE.SOMECOLUMN = :SOMEVALUE
ORDER BY SOMETABLE.SOMEOTHERCOLUMN;

The final answer will entirely depend on what database you're using.

回答3:

For MySql:

SELECT  @row := @row + 1 as row FROM anytable a, (SELECT @row := 0) r

回答4:

How you'd do that depends on your database server. In SQL Server, you could use row_number():

select  row_number() over (order by age)
,       age
,       count(*) as usercount 
from    users 
group by 
        age
order by
        age

But it's often easier and faster to use client side row numbers.

回答5:

use rownumber function available in sql server

SELECT 
    ROW_NUMBER() OVER (ORDER BY columnNAME) AS 'RowNumber',count(*) as usercount
    FROM users