Question

I have a table with an id and a value.
How can I rank an element of the table in order desc by its value?
What I want to do is:

SELECT id FROM table ORDER BY value DESC

And i want it to tell me for exemple the position of id=4

thanks a lot for answering!

Answer 1

MySQL does not have analytic functions, so you have to use user variables:

SELECT   @r:=@r+1 AS rank, id
FROM     table, (SELECT @r:=0) init
ORDER BY value DESC

To get the rank of a particular record, wrap it in an outer query:

SELECT rank FROM (
  SELECT   @r:=@r+1 AS rank, id
  FROM     table, (SELECT @r:=0) init
  ORDER BY value DESC
) t WHERE id = 4

To save MySQL from needlessly calculating the rank of every record in the table, you could add a filter:

SELECT rank FROM (
  SELECT   @r:=@r+1 AS rank, table.id
  FROM     table,
           (SELECT value FROM table WHERE id=4) t,
           (SELECT @r:=0) init
  WHERE    table.value >= t.value
  ORDER BY table.value DESC
) t WHERE id = 4