怎么得到同一条记录中的字段中的最大值和最小值

[LiMeisoft]

例如有A，B，C，D四个字段，要从，B，C，D中找出最大值和最小值
SELECT A，最大值，最小值 FROM TABLENAME

[victorycyz]

select a,max(b),min(b)
from
(
select a,b from tablename
union all
select a,c from tablename
union all
select a,d from tablename
) a
group by a

[li_sj]

写条简单点的

Select max(a) a From Tablename --求最大
Select min(b) b From Tablename --求最小
其原理同上

[zjcxc]

SELECT A,最大值=max(最大值),最小值 =min(最小值)
FROM(
select a,最大值=max(b),最小值=min(b) from TABLENAME group by a
union
select a,最大值=max(c),最小值=min(c) from TABLENAME group by a
union
select a,最大值=max(d),最小值=min(d) from TABLENAME group by a
)a
group by a