oracle 12c中增加自增长字段,还有序列吗

郑全

哪个能否验证一下

monkeybird

Identity Columns

 Improved Defaults 增强了DEFAULT, default目前可以直接指代sequence了，同时增强了default充当identity的能力

• Default to a sequence
• Default when null inserted
• Identity Type
• Metadata-only Defaults for NULL columns

Oracle Database 12c Release 1 implements ANSI-compliant IDENTITY columns. Migration from database systems that use identity columns is simplified and can take advantage of this new functionality.

This feature implements auto increment by enhancing DEFAULT or DEFAULT ON NULL semantics for use by SEQUENCE.NEXTVAL and SYS_GUID, supports built-in functions and implicit return of default values.

 

SQL> CREATE TABLE t1 (c1 NUMBER GENERATED BY DEFAULT ON NULL AS IDENTITY, c2 VARCHAR2(10));

 

Table created.

 

SQL> INSERT INTO t1(c2) VALUES ('abc');

 

1 row created.

SQL>INSERT INTO t1 (c1, c2) VALUES (null, 'xyz');

1 row created.

 

SQL> INSERT INTO t1 (c1, c2) VALUES (default,'jkl');

 

1 row created.

 

SQL> SELECT c1, c2 FROM t1;

        C1 C2
---------- ----------
         1 abc
         2 xyz
         3 jkl