根据MYSQL中同一表中的另一列更新列中的值

Question

I have a table that is having 3 columns

1. vid - auto increment column
2. video_id - containing numbers
3. a_id - containing junk numbers

The table looks like below.

Vid    Video_id    a_id
101     1            3
102     1            3
103     5            3
104     5            3
105     5            3
106     11           3
107     11           3
108     11           3
109     11           3
110     11           3         

I want to update a_id column values based on video_id values. Values in a_id should be updated as below.ex: If there are five 11 digit in video_id then the value in a_id should be updated 1 through 5.

Vid    Video_id    a_id
101     1            1
102     1            2
103     5            1
104     5            2
105     5            3
106     11           1
107     11           2
108     11           3
109     11           4
110     11           5

Answer 1

You can use user defined variables to give rank for each video group and then join with your real table by your auto increment column and update a_id accordingly

update t
join (
    SELECT 
    Vid,
    @r:= CASE WHEN Video_id = @g THEN @r+1  ELSE @r:=1 END a_id 
    ,@g:=Video_id
    FROM t,(SELECT @r:=0,@g:=0) t1
    ORDER BY Video_id
) t1
on(t.Vid =t1.Vid)
set t.a_id = t1.a_id

Demo