Mysql查询以替代方式打印数据库值

Question

我有一个数据库表，我必须按照以下方式打印

+---+--------+-----+    
|id | cat_id | name|    
+---+--------+-----+     
|1  |   1    | b   |    
|2  |   1    | ba  |    
|3  |   2    | c   |    
|4  |   2    | ca  |    
+---+--------+-----+

我需要一个mysql查询，它将以下列方式打印此表

+---+--------+-----+    
|id | cat_id | name|    
+---+--------+-----+     
|1  |   1    | b   |    
|3  |   2    | c   |    
|2  |   1    | ba  |    
|4  |   2    | ca  |    
+---+--------+-----+

提前致谢

Answer 1

select * from (
    select
    t.*,
    @catwise_rownum := if(@prevcat != cat_id, 1, @catwise_rownum + 1) as rownum,
    @prevcat := cat_id
    from
    your_table t,
    (select @catwise_rownum:=0, @prevcat:=null) var_init
    order by cat_id, id
) sq
order by rownum, cat_id

• 看到它在sqlfiddle
中正常工作