Question

我有两张桌子。第一个是学生表，他可以选择两个选修课程，其他表格是当前学期的可选课程列表。

当学生选择课程时，会插入行，其中包含基本详细信息，例如卷号，插入时间，所选课程和状态为“1”。当取消选择所选课程时，该行的状态设置为“0”。

假设学生选择了课程编号1和2。

现在使用此查询

select SselectedCourse AS [text()] FROM  Sample.dbo.Tbl_student_details where var_rollnumber = '020803009' and status = 1 order by var_courseselectedtime desc FOR XML PATH('')

这会给我结果为“12”，其中1是物理，2是社交。

第二个表保存1-9的值例如，课程id

1 = physics
2 = social
3 = chemistry
4 = geography
5 = computer
6 = Spoken Hindi
7 = Spoken English
8 = B.EEE
9 = B.ECE

现在当前学生选择了1和2.所以在第一栏，我得到“12”，第二栏我需要得到“3456789”（剩余课程）。如何为此编写查询？

Answer 1

这不是单一查询，而是简单。

DECLARE @STUDENT AS TABLE(ID INT, COURSEID INT)
DECLARE @SEM AS TABLE (COURSEID INT, COURSE VARCHAR(100))

INSERT INTO @STUDENT VALUES(1, 1)

INSERT INTO @STUDENT VALUES(1, 2)

INSERT INTO @SEM VALUES(1, 'physics')

INSERT INTO @SEM VALUES(2, 'social')

INSERT INTO @SEM VALUES(3, 'chemistry')

INSERT INTO @SEM VALUES(4, 'geography')

INSERT INTO @SEM VALUES(5, 'computer')

INSERT INTO @SEM VALUES(6, 'Spoken Hindi')

INSERT INTO @SEM VALUES(7, 'Spoken English')

INSERT INTO @SEM VALUES(8, 'B.EEE')

INSERT INTO @SEM VALUES(9, 'B.ECE')

DECLARE @COURSEIDS_STUDENT VARCHAR(100), @COURSEIDS_SEM  VARCHAR(100)

SELECT @COURSEIDS_STUDENT = COALESCE(@COURSEIDS_STUDENT, '') + CONVERT(VARCHAR(10), COURSEID) + ' ' FROM @STUDENT

SELECT @COURSEIDS_SEM = COALESCE(@COURSEIDS_SEM , '') + CONVERT(VARCHAR(10), COURSEID) + ' ' FROM @SEM WHERE COURSEID NOT IN (SELECT COURSEID FROM @STUDENT)


SELECT @COURSEIDS_STUDENT COURSEIDS_STUDENT, @COURSEIDS_SEM COURSEIDS_SEM

Answer 2

试试这个：

;WITH CTE as (select ROW_NUMBER() over (order by (select 0)) as rn,* from Sample.dbo.Tbl_student_details)

,CTE1 As(
select rn,SselectedCourse ,replace(stuff((select ''+courseid  from course_details for xml path('')),1,1,''),SselectedCourse,'') as rem from CTE a 
where rn = 1
union all
select c2.rn,c2.SselectedCourse,replace(rem,c2.SselectedCourse,'') as rem 
from CTE1 c1 inner join CTE c2
on c2.rn=c1.rn+1

)

select STUFF((select ''+SselectedCourse from CTE1 for xml path('')),1,0,''),(select top 1 rem from CTE1 order by rn desc)

比较sql server中的两列并返回剩余的数据

2 个答案: