Oracle学习记录之使用自定义函数和触发器实现主键动态生成

CREATE TABLE TENDER
(
 TENDER_ID  VARCHAR2(50) PRIMARY KEY,
 PROJECT_NAME VARCHAR2(50) NOT NULL UNIQUE,
 CONTENT   BLOB,
 END_DATE   DATE NOT NULL,
 STATUS    INTEGER NOT NULL
);
CREATE TABLE BID
(
 BID_ID  VARCHAR2(50) PRIMARY KEY,
 TENDER_ID VARCHAR2(50) NOT NULL,
 COMPANY  VARCHAR2(50) NOT NULL,
 CONTENT  BLOB,
 BID_DATE DATE NOT NULL,
 PRICE   INTEGER NOT NULL,
 STATUS  INTEGER NOT NULL
);
ALTER TABLE BID ADD CONSTRAINT FK_BID_TENDER_ID FOREIGN KEY(TENDER_ID) REFERENCES TENDER(TENDER_ID);

CREATE OR REPLACE 
FUNCTION "createZBNo" RETURN VARCHAR2
AS
hasCount NUMBER(11,0);
lastID VARCHAR2(50);
lastTime VARCHAR2(12);
lastNo NUMBER(3,0);
curNo NUMBER(3,0);
BEGIN
  -- 查询表中是否有记录
  SELECT "COUNT"(TENDER_ID) INTO hasCount FROM TENDER;
  IF hasCount > 0 THEN
    -- 查询必要信息
    SELECT TENDER_ID INTO lastID FROM TENDER WHERE ROWNUM = 1 ORDER BY to_number(to_char(scn_to_timestamp(ORA_ROWSCN),'yyyyMMddhh24mmss'),'99999999999999') DESC;
    SELECT "SUBSTR"(lastID, 3, 8) INTO lastTime FROM dual;
    -- 分析上一次发布招标信息是否是今日
    IF ("TO_CHAR"(SYSDATE,'YYYYMMDD') = lastTime) THEN
      SELECT "TO_NUMBER"("SUBSTR"(lastID, 11, 13), '999') INTO lastNo FROM dual;
      -- 如果是今日且流水号允许新增招标信息
      IF lastNo  999 THEN
        SELECT lastNo + 1 INTO curNo FROM dual;
        RETURN 'ZB'||lastTime||"LPAD"("TO_CHAR"(curNo), 3, '0');
      END IF;
        -- 流水号超出
        RETURN 'NoOutOfBounds!Check it!';
    END IF;
      -- 不是今日发布的招标信息，今日是第一次
      RETURN 'ZB'||"TO_CHAR"(SYSDATE,'YYYYMMDD')||'001';
  END IF;
      -- 整个表中的第一条数据
    RETURN 'ZB'||"TO_CHAR"(SYSDATE,'YYYYMMDD')||'001';
END;

CREATE OR REPLACE 
FUNCTION "createTBNo" (ZBNo IN VARCHAR2)
RETURN VARCHAR2
AS
hasCount NUMBER(11,0);
lastID VARCHAR2(50);
lastNo NUMBER(3,0);
curNo NUMBER(3,0);
BEGIN
  -- 查看是否已经有了对于该想招标的投标书
  SELECT "COUNT"(BID_ID) INTO hasCount FROM BID WHERE BID_ID LIKE 'TB'||ZBNo||'___' AND ROWNUM = 1 ORDER BY to_number(to_char(scn_to_timestamp(ORA_ROWSCN),'yyyyMMddhh24mmss'),'99999999999999') DESC;
  IF hasCount > 0 THEN
    -- 有了
    SELECT BID_ID INTO lastID FROM BID WHERE BID_ID LIKE 'TB'||ZBNo||'___' AND ROWNUM = 1 ORDER BY to_number(to_char(scn_to_timestamp(ORA_ROWSCN),'yyyyMMddhh24mmss'),'99999999999999') DESC;
      SELECT "TO_NUMBER"("SUBSTR"(lastID, 16,18),'999') INTO lastNo FROM dual;
      -- 流水号没超出
      IF lastNo  999 THEN
        SELECT lastNo + 1 INTO curNo FROM dual;
        RETURN 'TB'||ZBNo||"LPAD"("TO_CHAR"(curNo),3,'0');
      END IF;
        RETURN 'NoOutOfBounds!Check it!';
  END IF;
    -- 没有投标书对该招标书
    RETURN 'TB'||ZBNo||'001';
END;

CREATE OR REPLACE 
 TRIGGER newTender
 BEFORE INSERT 
 ON TENDER
 FOR EACH ROW
BEGIN
  -- 如果生成编号失败
 IF (LENGTH("createZBNo") > 13) THEN
    -- 此处根据我的提示信息报错可以直接如下操作
    -- :NEW.TENDER_ID := NULL;
  RAISE_APPLICATION_ERROR(-20222,"createZBNo");
 END IF;
    -- 如果生成编号成功，将编号注入查询语句中
   :NEW.tender_id :="createZBNo";
END;

CREATE OR REPLACE 
 TRIGGER newBid
 BEFORE INSERT 
 ON BID
 FOR EACH ROW
BEGIN
 IF (LENGTH("createTBNo"(:NEW.TENDER_ID)) > 18) THEN
  RAISE_APPLICATION_ERROR(-20222,"createTBNo"(:NEW.TENDER_ID));
 END IF;
   :NEW.BID_ID :="createTBNo"(:NEW.TENDER_ID);
END;