Mysql使用上一条记录中的值更新记录

Question

I have the following table, and what I'm trying to do is to update, for example, RefIDs 3-14 with the same Status value "Added" as the previous value. I want to do this until it reaches the next completed value. So when it encounters "Added", it updates all rows below that have a null with "Added" until it reaches the next RefID that has a populated Status, and subsequently updates the next batch of values. Can this be done? Any help would be greatly appreciated. I'm looking for this to be dynamic, as I don't want to manually update, say, Status = "Added" where RefID is 3.

RefID Status


1 Null


2 Added
3 Null
4 Null
5 Changed
6 Null
7 Null


2 Added
3 Null
4 Null
5 Changed
6 Null
7 Null


2 Added
3 Null
4 Null
5 Changed
6 Null
7 Null


2 Added
3 Null
4 Null
5 Changed
6 Null
7 Null


2 Added
3 Null
4 Null
5 Changed
6 Null
7 Null


2 Added
3 Null
4 Null
5 Changed
6 Null
7 Null


2 Added
3 Null
4 Null
5 Changed
6 Null
7 Null


2 Added
3 Null
4 Null
5 Changed
6 Null
7 Null


2 Added
3 Null
4 Null
5 Changed
6 Null
7 Null


2 Added
3 Null
4 Null
5 Changed
6 Null
7 Null


2 Added
3 Null
4 Null
5 Changed
6 Null
7 Null


2 Added
3 Null
4 Null
5 Changed
6 Null
7 Null

What I want to achieve is this:

RefID Status


1 Null


2 Added
3 Added
4 Added
5 Changed
6 Changed
7 Changed


2 Added
3 Added
4 Added
5 Changed
6 Changed
7 Changed


2 Added
3 Added
4 Added
5 Changed
6 Changed
7 Changed


2 Added
3 Added
4 Added
5 Changed
6 Changed
7 Changed


2 Added
3 Added
4 Added
5 Changed
6 Changed
7 Changed


2 Added
3 Added
4 Added
5 Changed
6 Changed
7 Changed


2 Added
3 Added
4 Added
5 Changed
6 Changed
7 Changed


2 Added
3 Added
4 Added
5 Changed
6 Changed
7 Changed


2 Added
3 Added
4 Added
5 Changed
6 Changed
7 Changed


2 Added
3 Added
4 Added
5 Changed
6 Changed
7 Changed


2 Added
3 Added
4 Added
5 Changed
6 Changed
7 Changed


2 Added
3 Added
4 Added
5 Changed
6 Changed
7 Changed

Answer 1

Try this query -

UPDATE refs_table t1
  JOIN (
    SELECT RefID, @s:=IF(Status IS NULL, @s, Status) Status
      FROM (SELECT * FROM refs_table ORDER BY RefID) r,
    (SELECT @s:=NULL) t
  ) t2
  ON t1.RefID = t2.RefID
SET t1.Status = t2.Status

Answer 2

UPDATE
    TableX AS t
JOIN
    TableX AS tu
ON tu.RefID = (
    SELECT 
        MAX(prev.RefID)
    FROM 
        TableX AS prev
    WHERE 
        prev.RefID < t.RefID AND 
        prev.Status IS NOT NULL) 
SET
    t.Status = tu.Status
WHERE
    t.Status IS NULL

Answer 3

You can do it with a cursor. http://dev.mysql.com/doc/refman/5.0/en/cursors.html

EDIT: Okay, okay, I read the other answers. Way better. Cursor is overkill here.