新增流水号

Create FUNCTION [dbo].[get_SerialNo]()
RETURNS VARCHAR(20)
AS
BEGIN 
declare
@x1 int,
@y1 char(8),
@z1 varchar(30)
select @x1= COUNT(SaleID) from SalesActivity where CAST(CreateDt as date)=CAST(GETDATE() as date)
if(@x1=0)
  begin
  select @y1=convert(char(8),getdate(),112)
  select @z1= 'CX'+@y1+'0001'
  end
else
 begin 
 select @z1='CX'+cast((select MAX(CAST( SUBSTRING(SaleID,3,12) as bigint))+1 from SalesActivity where CAST(CreateDt as date)=CAST(GETDATE() as date))as varchar(50))
 
  --insert TestNo(CharNo,DT)
  --values( 'WT'+cast((select MAX(CAST( SUBSTRING(charno,3,12) as bigint))+1 from TestNo where CAST(DT as date)=CAST(GETDATE() as date))as varchar(50)) ,GETDATE())
 end
 return @z1
end