SQL serial number acquisition code example

CREATE TABLE tb_b_Seq( 
Year int, -- year Month int, -- month Attr varchar(50), -- attribute Seq int -- serial number)

create Proc GetSeq ( 
@attr varchar(50),
@year int, 
@month int, 
@Return int output ) 
As 
set @Return=(select top 1 Seq from tb_b_Seq where Attr=@attr and MONTH=@month and YEAR=@year) 
if(@Return is null) 
begin 
 set @Return=1 
 insert into FMDS_tb_b_Seq (Attr,Year,Month,Seq) values ​​(@attr,@year,@month,@Return) 
end 
else 
begin 
 set @Return=@Return+1 
 update FMDS_tb_b_Seq set Seq=@Return where Attr=@attr and MONTH=@month and YEAR=@year 
end

declare @ret int 
exec GetSeq 'Contract',2017,10,@ret 
print @ret