动态
很多时候我们需要得到交叉列表，最近做课程设计就需要这样的功能，比如要得到一个班某学期的成绩，因为每一学期所学科目和数量都是变化的，这就要求动态的查询以得到成绩。而且得到这样的显示形式：
studentID studentName courseName1 courseName2 courseName3 ……
1 lupenda 66 77 88 ……
。
。
。
下面的例子就是为了实现上面的功能，该存取过程涉及3张表：
Course表：
CourseID，CourseName,Duration,[Year],MajorID,Semester
StudentData表：
StudentID,StudentName,ClassID……
Student_Course表：
StudentID，CourseID，Score
--根据不同参数取得成绩
--可以得到某学期，某专业，某班级，某学生的成绩
CREATE procedure GetScore
@Year int ,@Semester bit ,@MajorID int = null,@ClassID int = null,@StudentID int = null
as
declare @var varchar(200)
declare @sql varchar(8000)
set @sql=''
--放进临时表
select distinct CourseName into #tb from Course where Course.Year = @Year and Course.Semester = @Semester
--声明游标
declare cur cursor
for select CourseName from #tb
open cur
fetch next from cur into @var
while @@fetch_status=0
begin
set @sql = @sql + 'sum(case when Course.CourseName = ''' +@var+ ''' then Student_Course.Score else 0 end) as '+ @var+','
fetch next from cur into @var
end
set @sql = left(@sql,len(@sql)-1)
set @sql = 'select Class.ClassName as 班级,Student_Course.StudentID as 全学号,StudentData.StudentName as 姓名, ' +@sql+ '
from StudentData,Student_Course,Course ,Class
where Student_Course.CourseID = Course.CourseID
and StudentData.StudentID = Student_Course.StudentID
and StudentData.ClassID = Class.ClassID'
--根据输入参数的不同创建查询语句
if @Year is not null
set @sql = @sql+ ' and Course.Year = '+ Cast( @Year as varchar(4)) --强制转换为字符串
if @Semester is not null
set @sql = @sql+ ' and Course.Semester = '+ Cast( @Semester as varchar(1))
if @MajorID is not null
set @sql = @sql+ ' and Course.MajorID = '+ Cast( @MajorID as varchar(4))
if @ClassID is not null
set @sql = @sql+ ' and StudentData.ClassID = '+ Cast( @ClassID as varchar(4))
if @StudentID is not null
set @sql = @sql+ ' and StudentData.StudentID = '+ Cast( @StudentID as varchar(8))
set @sql = @sql+ 'group by Class.ClassName,Student_Course.StudentID,StudentData.StudentName order by Student_Course.StudentID '
exec(@sql)
deallocate cur
drop table #tb
GO
至此，该存取过程实现了我们想要的功能.第一次发文章，请大家多多支持！