MySQL - Get row number on select

Question

Can I run a select statement and get the row number if the items are sorted?

I have a table like this:

mysql> describe orders;
+-------------+----         


        

Answer 1

Take a look at this.

Change your query to:

SET @rank=0;
SELECT @rank:=@rank+1 AS rank, itemID, COUNT(*) as ordercount
  FROM orders
  GROUP BY itemID
  ORDER BY ordercount DESC;
SELECT @rank;

The last select is your count.

Answer 2

It's now builtin in MySQL 8.0 and MariaDB 10.2:

SELECT
  itemID, COUNT(*) as ordercount,
  ROW_NUMBER OVER (PARTITION BY itemID ORDER BY rank DESC) as rank
FROM orders
GROUP BY itemID ORDER BY rank DESC

Answer 3

Swamibebop's solution works, but by taking advantage of table.* syntax, we can avoid repeating the column names of the inner select and get a simpler/shorter result:

SELECT @r := @r+1 , 
       z.* 
FROM(/* your original select statement goes in here */)z, 
(SELECT @r:=0)y;

So that will give you:

SELECT @r := @r+1 , 
       z.* 
FROM(
     SELECT itemID, 
     count(*) AS ordercount
     FROM orders
     GROUP BY itemID
     ORDER BY ordercount DESC
    )z,
    (SELECT @r:=0)y;

Answer 4

SELECT @rn:=@rn+1 AS rank, itemID, ordercount
FROM (
  SELECT itemID, COUNT(*) AS ordercount
  FROM orders
  GROUP BY itemID
  ORDER BY ordercount DESC
) t1, (SELECT @rn:=0) t2;

Answer 5

You can use MySQL variables to do it. Something like this should work (though, it consists of two queries).

SELECT 0 INTO @x;

SELECT itemID, 
       COUNT(*) AS ordercount, 
       (@x:=@x+1) AS rownumber 
FROM orders 
GROUP BY itemID 
ORDER BY ordercount DESC;