게시글의 상위/하위 게시물을 가져오는 쿼리를 만들고 싶은데

스토어드 프로시져로 만들고자 하는제 자꾸 else 키워드 근처의 구문이 잘못 됐다고만 하네요

부탁드립니다.

create proc board_updown_info
@info_flag char(4),
@board_no int,
@board_root int,
@board_step int,
@check int output
as

set @check=0

if @info_flag='up'
if (select top 1 count(board_code),board_code,board_title from board where board_number='+@board_no+' and board_root='+@board_root+' and board_step<'+@board_step+' group by board_code order by board_root asc,board_step desc)=1
set @check=1
begin
select top 1 board_code,board_title from board where board_number='+@board_no+' and board_root='+@board_root+' and board_step<'+@board_step+' group by board_code order by board_root asc,board_step desc
end
else
begin
if (select top 1 count(board_code) from board where board_number='+@board_no+' and board_root>'+@board_root+' group by board_code order by board_root asc,board_step desc)=1
set @check=1
begin
select top 1 board_code,board_title from board where board_number='+@board_no+' and board_root>'+@board_root+' group by board_code order by board_root asc,board_step desc
end

end

else @info_flag='down'
if (select top 1 count(board_code) from board where board_number='+@board_no+' and board_root='+@board_root+' and board_step>'+@board_step+' group by board_code order by board_root desc,board_step)=1
set @check=1
begin
select top 1 board_code,board_title from board where board_number='+@board_no+' and board_root='+@board_root+' and board_step>'+@board_step+' group by board_code order by board_root desc,board_step
end
else
if (select top 1 count(board_code) from board where board_number='+@board_no+' and board_root<'+@board_root+' group by board_code order by board_root desc,board_step)=1
set @check=1
begin
select top 1 board_code,board_title from board where board_number='+@board_no+' and board_root<'+@board_root+' group by board_code order by board_root desc,board_step
end