select top 20 * from code_kcm where xh='瀛﹀彿' order by 鑰冭瘯瀛﹀勾
union all
select top 20 * from code_kcm where xh='瀛﹀彿' order by 鑰冭瘯瀛﹀勾 DESC
union all
select top 20 * from code_kcm where xh='瀛﹀彿' order by 鑰冭瘯瀛﹀勾 DESC
union all
select top 20 * from code_kcm where xh='学号' order by 考试学年 DESC
select top 50 percent * from code_kcm where xh='学号' order by 考试学年--后一半的数据
select top 50 percent * from code_kcm where xh='学号' order by 考试学年 desc
union all
select top 20 * from code_kcm where xh='学号' order by 考试学年 desc
select top 20 * from code_kcm where xh='学号' order by 考试学年--后一半的数据
select top 20 * from code_kcm where xh='学号' order by 考试学年 desc