交叉表

 

下面说一下交叉表的概念
说到交叉表先提一下递归的select变量
递归的select变量可以使用select语句和子查询将一个变量与其自身拼接起来。
举一个例子
select @var=@var +d.column from table1 a
从而将基础表中垂直的列数据改为水平方向的数据。这样就可以替代游标。
下面就是动态交叉表和静态的交叉表的一个比较，动态的交叉表这样就代替了传统的游标。
交叉表
方法1
select  f_nUMBER as '学员',
SUM(case f_subject when 'A01' then f_nUM end) as 'A01',
SUM(case f_subject when 'A02' then f_nUM end) as 'A02' ,
SUM(case f_subject when 'A03' then f_nUM end) as 'A03' ,
SUM(case f_subject when 'A04' then f_nUM end) as 'A04' ,
SUM(case f_subject when 'A05' then f_nUM end) as 'A05' ,
SUM(case f_subject when 'A06' then f_nUM end) as 'A06' ,
SUM(case f_subject when 'A07' then f_nUM end) as 'A07' ,
SUM(case f_subject when 'A08' then f_nUM end) as 'A08' ,

SUM(case f_subject when 'A09' then f_nUM end) as 'A09'
from rowdata group by f_nUMBER order by f_nUMBER

 

方法2
declare @sql nvarchar(2000)
set @sql=''
select @sql=@sql+ 'sum(case F_subject when '''+ a.F_subject +''' then F_Num else 0 end) as '
+a.F_Name+','
from (select  distinct top 100 percent F_subject,F_Name from rowdata b JOIN SUBJECT_name c on b.F_subject=c.F_number order by F_subject ) a
set @sql='select f_nUMBER as '+'"学员",'+@sql + 'count(F_Number) as '+'"考试数目"'+
'from rowdata group by F_Number order by F_Number'
print @sql
exec sp_executesql @sql