SQL语句和存储过程 查询语句的流程控制

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

以上这些SQL语句能不能转成一个？我自己试了下
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
但是这样的话，这个存储过程就有6个变量，实际上应该只提供一个变量就可以了

主要的问题就是自己没搞清楚 @a,@b,@C,@d 等是临时变量，是放在as后面重新做一些申明的，而不是放在开头整个存储过程的变量定义。