Row number per group in mysql

Question

I want to produce query result base on this scenario that can create row number according to crew_id and type.

id   crew_id   amount    type
 1      4                


        

Answer 1

In addition to the answer of @Janty here is a solution if you want to UDATE your table with the rownumber:

UPDATE myTable mt,(SELECT @curRow := 0, @curType := '') r SET type=
    ( 
        CASE type 
            WHEN @curType
        THEN @curRow := @curRow + 1 
        ELSE @curRow := 1 AND @curType := type END
      )
;

As janty too crewId is not within. Use a second "case" for that as mentioned in the other answers.