oracle Oracle数据库中的自增主键
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Autoincrement Primary key in Oracle database
提问by GigaPr
I would like to achieve an identity or auto-incrementing value in a column ala SQL Server:
我想在列 ala SQL Server 中实现标识或自动递增值：
CREATE TABLE RollingStock
(
Id NUMBER IDENTITY(1,1),
Name Varchar2(80) NOT NULL
);
How can this be done?
如何才能做到这一点？
回答by Matthew Watson
As Orbman says, the standard way to do it is with a sequence. What most people also do is couple this with an insert trigger. So, when a row is inserted without an ID, the trigger fires to fill out the ID for you from the sequence.
正如 Orbman 所说，执行此操作的标准方法是使用序列。大多数人还做的是将其与插入触发器结合使用。因此，当插入没有 ID 的行时，触发器会触发以从序列中为您填写 ID。
CREATE SEQUENCE SEQ_ROLLINGSTOCK_ID START WITH 1 INCREMENT BY 1 NOCYCLE;
CREATE OR REPLACE TRIGGER BI_ROLLINGSTOCK
BEFORE INSERT ON ROLLINGSTOCK
REFERENCING OLD AS OLD NEW AS NEW
FOR EACH ROW
WHEN (NEW.ID IS NULL)
BEGIN
select SEQ_ROLLINGSTOCK_ID.NEXTVAL
INTO :NEW.ID from dual;
END;
This is one of the few cases where it makes sense to use a trigger in Oracle.
这是在 Oracle 中使用触发器有意义的少数情况之一。
回答by Adam Hawkes
If you really don't care what the primary key holds, you can use a RAW type for the primary key column which holds a system-generated guid in binary form.
如果您真的不关心主键包含什么，您可以对主键列使用 RAW 类型，该列以二进制形式保存系统生成的 guid。
CREATE TABLE RollingStock
(
ID RAW(16) DEFAULT SYS_GUID() PRIMARY KEY,
NAME VARCHAR2(80 CHAR) NOT NULL
);
