单行/单列查询（MySQL）

Question

我有这张桌子： datatable 我想写一个查询，用下面的数字更新整个99，这样每个99将被下面的数字替换，每个空白名称，下面的名称。

我试过了：

update datatable.code set datatable.code= previous (datatable.code)
WHERE datatable.code=99;

Answer 1

update abc set code =
 CASE WHEN name='Jean' THEN 1
      WHEN name='Peter' THEN 2
 END 
 where code=99;

Answer 2

使用没有更新的mysql

select *, 
if(ta.code!=99,ta.code, select ta2.code from table_a as ta2 where ta2.ID_q=ta.ID_q and ta.code!=99 limit 1) as code_a,
if(ta.name!='',ta.name, select ta2.name from table_a as ta2 where ta2.ID_q=ta.ID_q and ta.name!='' limit 1) as name_a 
from table_a as ta;