updating columns with a sequence number mysql

Question

I have a table with the columns: (this is only an example I have 50K records)

Name,   Number

Joe     Null
Michael Null
Moses   Null

I to u

Answer 1

SET @rank:=0;
update T
set Number=@rank:=@rank+1;

UPDATE

alternative way with one statement

UPDATE T
JOIN (SELECT @rank := 0) r
SET Number=@rank:=@rank+1;