Oracle中序列（SEQUENCE）的使用一例

create or replace trigger TRI_SUPPLIER
before insert on   SUPPLIER
for each row
begin
select seq_supid.NEXTVAL into:new.supcode from dual;
select seq_supid.CURRVAL into:new.supID from dual;
end;

create or replace trigger TRI_SUPPLIER
before insert on   SUPPLIER
for each row
declare  v_supval number(20);
begin
select  seq_supid.NEXTVAL into v_supval  from dual;
select v_supval  into:new.supcode from dual;
select v_supval  into:new.supID from dual;
end;

CREATE OR REPLACE TRIGGER TRI_ASSETPROJECT
BEFORE INSERT ON ASSETPROJECT
FOR EACH ROW
DECLARE V_PROJECTID NUMBER(20) :=0;
V_TMP VARCHAR2(100) :='';
BEGIN
SELECT :NEW.PROJECTCODE INTO V_TMP FROM DUAL;
dbms_output.put_line(V_TMP);
SELECT PROJECTID INTO V_PROJECTID  FROM ASSETPROJECT WHERE PROJECTCODE = :NEW.PROJECTCODE and rownum=1 ;
IF (NVL(V_PROJECTID,0)<=0) THEN ----如果不存在编码记录
begin
SELECT SEQ_ASSETPROJECTID.NEXTVAL INTO :NEW.PROJECTID FROM DUAL;
dbms_output.put_line('New ID ');
end;
ELSE --如果已存在编码记录
begin
--SELECT :V_PROJECTID INTO:NEW.PROJECTID FROM DUAL;
RAISE_APPLICATION_ERROR(-20001, '项目编码已存在，不允许重复添加！');
dbms_output.put_line('Old ID ');
end;
end if;
END;