Row_Number() in MySQL

ROW_NUMBER() in MySQL

I want the row with the single highest col3 for each (col1, col2) pair.

That's a groupwise maximum, one of the most commonly-asked SQL questions (since it seems like it should be easy, but actually it kind of isn't).

I often plump for a null-self-join:

SELECT t0.col3
FROM table AS t0
LEFT JOIN table AS t1 ON t0.col1=t1.col1 AND t0.col2=t1.col2 AND t1.col3>t0.col3
WHERE t1.col1 IS NULL;

“Get the rows in the table for which no other row with matching col1,col2 has a higher col3.” (You will notice this and most other groupwise-maximum solutions will return multiple rows if more than one row has the same col1,col2,col3. If that's a problem you may need some post-processing.)

Cannot find ROW_NUMBER() function in mysql 8.0.17?

row is a reserved word in mysql 8.0.2+ according to the documentation.

This should work:

SELECT custid, 
email, 
ROW_NUMBER() OVER ( PARTITION BY email ORDER BY email ) AS `row` 
FROM customers;

Or you can ditch row for something non-problematic such as AS rn.

Notice that partitioning by email and ordering by it at the same time doesn't make much sense.

Fiddle

How to add row number to an MySQL display using ROW_NUMBER()

Window functions evaluate after GROUP BY aggregation has happened, so it doesn't make much sense to use a partition on the name, since each record at that point would be guaranteed to have a distinct name. Most likely, you want something like this:

SELECT
    name, 
    ROW_NUMBER() OVER (ORDER BY AVG(work_days), COUNT(*) DESC) AS row_num,
    AVG(work_days) AS workday_average, 
    COUNT(*) AS count
FROM work
GROUP BY
    name
HAVING
   workday_average > 2
ORDER BY
    workday_average,
    count DESC;

But this of course assumes that you are using MySQL 8+. If not, then ROW_NUMBER won't be available.

Mysql row_number rank based on value

Rank window function seems the obvious answer, btw partition by is optional

create table t
(player_id int, value int);
insert into t values
(        10 ,   333 ),
(        11 ,    31 ),
(        15 ,    12 ),
(         9 ,     3 ),
(         1 ,     0 ),
(         8 ,     0 ),
(        12 ,     0 ),
(        13 ,     0 ),
(        14 ,     0 );

select *,
        rank() over (order by value desc)
from t

+-----------+-------+-----------------------------------+
| player_id | value | rank() over (order by value desc) |
+-----------+-------+-----------------------------------+
|        10 |   333 |                                 1 |
|        11 |    31 |                                 2 |
|        15 |    12 |                                 3 |
|         9 |     3 |                                 4 |
|        13 |     0 |                                 5 |
|        14 |     0 |                                 5 |
|         1 |     0 |                                 5 |
|         8 |     0 |                                 5 |
|        12 |     0 |                                 5 |
+-----------+-------+-----------------------------------+
9 rows in set (0.001 sec)

and if you only want for 11 put code in cte

with cte as
(select *,
        rank() over (order by value desc) rnk
from t
)
select player_id, rnk
from cte 
where player_id = 11;

ROW_NUMBER() equivalent in MySQL for inserting

Unfortunately, there is no ROW_NUMBER() equivalent in MySQL but you can still simulate it by creating a simple variable which holds a value an increment it every row.

Example:

SET @rank=0;
SELECT   @rank := @rank+1 AS rank, fruit, amount
FROM     sales
ORDER BY amount DESC;

SQLFiddle Demo

Row_Number() in MySQL