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

Here is my answer using only one case that creates row number according to both columns:

SELECT id, crew_id, amount, type,
   (CASE CONCAT(crew_id, type) 
        WHEN @cur_crew_type
        THEN @curRow := @curRow + 1
        ELSE @curRow := 0 END) + 1 AS cnt,
    @cur_crew_type := CONCAT(crew_id, type) AS cur_crew_type
FROM TABLE t,
     (SELECT @curRow := 0, @cur_crew_type := '') counter
      ORDER BY crew_id, type;

Answer 2

Please go through my fiddle

This One Last Tried

    SELECT    id,
              crew_id,
              amount,
              type,
             ( 
                CASE type 
                WHEN @curType 
                THEN @curRow := @curRow + 1 
                ELSE @curRow := 1 AND @curType := type END
              ) + 1 AS rank
    FROM      Table1 p,
              (SELECT @curRow := 0, @curType := '') r
   ORDER BY  crew_id,type asc;

Answer 3

SELECT id, crew_id, amount, type,
       ( 
        CASE type 
          WHEN @curType 
          THEN @curRow := @curRow + 1 
          ELSE @curRow := 1 AND @curType := type  END
      ) + 1 AS rank
 FROM      Table1 p,
      (SELECT @curRow := 0, @curType := '') r
   ORDER BY  crew_id, type asc;

Answer 4

@Janty's answer does not work when the type starts with a number (the rank starts at 2 instead of 1).

Use the following instead:

SELECT id,
     crew_id,
     amount,
     CASE type 
         WHEN @curType THEN @curRow := @curRow + 1 
         ELSE @curRow := 1
     END AS rank,
     @curType := type AS type
FROM Table1 p
JOIN (SELECT @curRow := 0, @curType := '') r
ORDER BY crew_id, type

Answer 5

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.

Answer 6

The question is quite old. But I would like to post it in case someone will have a same problem.

First of all, described answers do not work correct. For example, for

id   crew_id   amount    type
1      4       1000      AUB
2      4       1500      AUB
5      5       1000      AUB
6      6       3000      AUB
8      6       3500      AUB
9      4       5000      AUB

(I just removed rows with type 'CA') the result table will be

id   crew_id   amount    rank   type
1      4       1000      1      AUB
2      4       1500      2      AUB
9      4       5000      3      AUB
5      5       1000      4      AUB
6      6       3000      5      AUB
8      6       3500      6      AUB

So in fact it doesn't use both crew_id and type, it just uses type.

Here is how I solved this problem (probably there is a more elegant way to do it than use two nested 'CASE's, but you get the idea):

SELECT id,
    amount,
    CASE crew_id 
        WHEN @curCrewId THEN
            CASE type 
                WHEN @curType THEN @curRow := @curRow + 1 
                ELSE @curRow := 1
            END
        ELSE @curRow :=1
    END AS rank,
    @curCrewId := crew_id AS crew_id,
    @curType := type AS type
FROM Table1 p
JOIN (SELECT @curRow := 0, @curCrewId := 0, @curType := '') r
ORDER BY crew_id, type

The main idea remain. I just added a variable @curCrewId. If someone need to use 3 variables for grouping, so just use 3 variables and 3 nested 'CASE's. :)