[英]Unique value generation for primary key for multiple tables
我有3張桌子。 我想為每個下表生成ID,並且在每個表中應該是唯一的。 表1的ID-主ID 1-> 2-> 3表2的ID-主ID 4-> 5表3的ID-主ID 6-> 7-> 8每當對以上表進行新輸入時,它應在整個表中生成唯一值下次要在表1中插入2條記錄時,應為Table1 ID-主ID 9-> 10。
我們可以在Oracle中創建觸發器來完成此操作嗎
在每個表上使用觸發器並創建一個序列
CREATE SEQUENCE seq
START WITH 1
INCREMENT BY 1
NOCACHE
NOCYCLE;
然后在插入觸發器上執行以下操作:
select seq.nextval
into :new.id
from dual;
這是以前問過的。 看這里
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;
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