怎么取一行的最大值
表如下   
 TR1      TR2      TR3      TR4      TR5      TR6      AR1      AR2      AR3      AR4      AR5      AR6 
 1            2            3            4            5            6            12         11         10         9            8            7   
 怎么取出 
 TR1——TR6的最大值6 
 AR1——AR6的最大值12 
------解决方案--------------------TR1  TR2  TR3  TR4  TR5  TR6  AR1  AR2  AR3  AR4  AR5  AR6 
 1    2    3    4    5    6    12   11   10   9    8    7   
 怎么取出 
 TR1——TR6的最大值6 
 AR1——AR6的最大值12 
 select id , max(data) as data from 
 ( 
 select id =  'tr ' , tr1 as data 
 union all 
 select id =  'tr ' , tr2 as data 
 union all 
 select id =  'tr ' , tr3 as data 
 union all 
 select id =  'tr ' , tr4 as data 
 union all 
 select id =  'tr ' , tr5 as data 
 union all 
 select id =  'tr ' , tr6 as data 
 union all 
 select id =  'ar ' , ar1 as data 
 union all 
 select id =  'ar ' , ar2 as data 
 union all 
 select id =  'ar ' , ar3 as data 
 union all 
 select id =  'ar ' , ar4 as data 
 union all 
 select id =  'ar ' , ar5 as data 
 union all 
 select id =  'ar ' , ar6 as data 
 ) t 
 group by id
------解决方案--------------------selct 
     max(TR),max(AR) 
 from 
     (select TR1 as TR,AR1 as AR from t 
      union  
      select TR2,AR2 from t 
      union 
      select TR3,AR3 from t 
      union 
      select TR4,AR4 from t 
      union 
      select TR5,AR5 from t 
      union 
      select TR6,AR6 from t) a