SQL語句和存儲過程 查詢語句的流程控制

drop table classname
declare @TeacherID int
declare @a char(50)
declare @b char(50)
declare @c char(50)
declare @d char(50)
declare @e char(50)
set @TeacherID=1

select @a=DRClass1, @b=DRClass2, @c=DRClass3, @d=DRClass4, @e=DRClass5 from Teacher Where TeacherID = @TeacherID

create table classname(classname char(50))
insert into classname (classname) values (@a)
if (@b is not null)
begin
insert into classname (classname) values (@b)

if (@c is not null)
begin
insert into classname (classname) values (@c)

if (@d is not null)
begin
insert into classname (classname) values (@d)
if (@e is not null)
begin
insert into classname (classname) values (@e)
end
end
end
end

select * from classname

以上這些SQL語句能不能轉成一個存儲過程？我自己試了下
ALTER PROCEDURE Pr_GetClass

@TeacherID int,
@a char(50),
@b char(50),
@c char(50),
@d char(50),
@e char(50)
as

select @a=DRClass1, @b=DRClass2, @c=DRClass3, @d=DRClass4, @e=DRClass5 from Teacher Where TeacherID = @TeacherID
DROP TABLE classname
create table classname(classname char(50))

insert into classname (classname) values (@a)
if (@b is not null)
begin
insert into classname (classname) values (@b)

if (@c is not null)
begin
insert into classname (classname) values (@c)

if (@d is not null)
begin
insert into classname (classname) values (@d)
if (@e is not null)
begin
insert into classname (classname) values (@e)
end
end
end
end

select * from classname
但是這樣的話，這個存儲過程就有6個變量，實際上應該只提供一個變量就可以了

主要的問題就是自己沒搞清楚 @a,@b,@C,@d 等是臨時變量，是放在as后面重新做一些申明的，而不是放在開頭整個存儲過程的變量定義。

寫好的存儲過程如下

create  PROCEDURE  Pr_GetClass  
@TeacherID  int
as 

Declare @a  char(50), @b  char(50), @c  char(50), @d  char(50), @e  char(50) 
select  @a=DRClass1,  @b=DRClass2,  @c=DRClass3,  @d=DRClass4,  @e=DRClass5  from  Teacher  Where  TeacherID  =  @TeacherID 
DROP  TABLE  classname 
create  table    classname(classname  char(50)) 
insert  into  classname    (classname)  values  (@a) 
if  (@b  is  not  null)   
begin 
insert  into  classname    (classname)  values  (@b) 
if  (@c  is  not  null) 
   begin 
       insert  into  classname    (classname)  values  (@c) 
       if  (@d  is  not  null)   
       begin 
           insert  into  classname    (classname)  values  (@d) 
           if  (@e  is  not  null)   
           begin 
              insert  into  classname    (classname)  values  (@e) 
           end 
       end 
   end 
end  
select  *  from  classname
go

2 連表查詢

我有三個表
KJ表
KJID
TeacherID
..........................................................

Teacher表

TeacherID
TeacherName
CollageID
.........................................................

Collage表

CollageID
CollageName

我想寫一個SQL語句，查詢所有的KJ，根據KJ的TeacherID查到TeacherName,同時根據TeacherID查到Teacher，Teacher的CollageID查到Collage，最后生成的數據集里KJ的屬性里除了本身的KJName以外，還想加上TeacherName，CollageName。

語句如下

   SELECT T1.KJName, T2.TeacherName, T3.CollageName
   FROM KJ T1
   LEFT JOIN Teacher T2 ON T2.TeacherID=T1.TeacherID
   LEFT JOIN Collage T3 ON T3.CollageID=T2.CollageID