postgresql 日期生成流水号

 --表结构
 DROP TABLE if exists public.sys_tabid;
 CREATE TABLE public.sys_tabid
 (
   id serial NOT NULL ,
   type character varying(50),
   code character varying(50) NOT NULL,
   seed integer,
   date date
 );
 --测试数据
 insert into sys_tabid(type,code,seed,date) values
 ('订单PO','',1,'2017-06-27'),
 ('仓库','',1,'2017-06-27'),
 ('入库PO','',1,'2017-06-27');

 --公共函数
 CREATE OR REPLACE FUNCTION public.p_sys_getid(
     p_type character varying DEFAULT '仓库'::character varying,
     p_seed integer DEFAULT 1)
   RETURNS integer AS
 $BODY$
 DECLARE
 --SET NOCOUNT ON;
 DECLARE
     v_d date := now()::date;
     v_code INT := 0;
     v_rowcount INTEGER;

 BEGIN
 -- select * from p_sys_getid();
 <<tran>>
 loop
 <<TRY>>
 loop
      --IF  NOT EXISTS(SELECT 1 FROM [Sys_TabID] WITH(ROWLOCK) WHERE [type]=@type AND [date]=@d) 

     IF  NOT EXISTS(SELECT 1 FROM Sys_TabID WHERE type = p_type AND date=v_d) then
         INSERT INTO Sys_TabID(type,code,seed,date) values(p_type,'',p_seed,v_d);
         GET DIAGNOSTICS v_rowcount = ROW_COUNT;
     end if;

     IF v_rowcount > 0 then
          v_code=1;
         exit tran;
     END IF;

     select code::int+seed::int from Sys_TabID into v_code WHERE type = p_type AND date = v_d;
     UPDATE Sys_TabID SET code = v_code WHERE type = p_type AND date = v_d;
         GET DIAGNOSTICS v_rowcount = ROW_COUNT;
         IF v_rowcount>0 then
             exit tran;
          end if;

 exit TRY;
 exit tran;

 END LOOP;
 END LOOP;

 RETURN v_code;

 END;
 $BODY$
   LANGUAGE plpgsql 

 --查询函数
 CREATE OR REPLACE FUNCTION public.select_tlsh(
     letter character varying DEFAULT 'DGR'::character varying,
     p_type character varying DEFAULT '订单PO'::character varying)
   RETURNS character varying AS
 $BODY$
 DECLARE
     --letter varchar(10)='DGR';
     id int;
     TLSH VARCHAR(20);
 BEGIN
     select * from P_Sys_GetID(p_type,1) into id;
         TLSH = letter||to_char(now()::timestamp,'YYYYMMDD')||right((1000000+id)::varchar,6);
          RETURN TLSH;
 END;
 $BODY$
   LANGUAGE plpgsql