Question

我有3张桌子。我想为每个下表生成ID，并且每个表都应该是唯一的。表1 ID - 主要 ID 1 - ＆gt; 2 - ＆gt; 3 表2 ID - 主要 ID 4 - ＆gt;五表3 ID - 主要 ID 6 - ＆gt; 7 - ＆gt; 8 每当对上表进行新的输入时，它应该在表中生成唯一值下次我要将2条记录插入表1时应该是表1 ID - 主要 ID 9 - ＆gt; 10。

我们是否可以在Oracle

中创建触发器来完成此任务

Answer 1

在每张桌子上使用触发器并创建Sequence

CREATE SEQUENCE seq
 START WITH     1
 INCREMENT BY   1
 NOCACHE
 NOCYCLE;

然后在插入触发器上执行以下操作：

   select seq.nextval 
     into :new.id
     from dual;

之前有人问过。看here

CREATE OR REPLACE TRIGGER my_trigger
  BEFORE INSERT 
  ON qname
  FOR EACH ROW
  -- Optionally restrict this trigger to fire only when really needed
  WHEN (new.qname_id is null)
DECLARE
  v_id qname.qname_id%TYPE;
BEGIN
  -- Select a new value from the sequence into a local variable. As David
  -- commented, this step is optional. You can directly select into :new.qname_id
  SELECT qname_id_seq.nextval INTO v_id FROM DUAL;

  -- :new references the record that you are about to insert into qname. Hence,
  -- you can overwrite the value of :new.qname_id (qname.qname_id) with the value
  -- obtained from your sequence, before inserting
  :new.qname_id := v_id;
END my_trigger;

多个表的主键的唯一值生成

1 个答案: