oracle 自增列查询

SQL> CREATE TABLE employees (
  2    id   NUMBER GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
  3    name VARCHAR2(100)
  4  );

Table created.

SQL> CREATE TABLE employees1 (
  2    id   NUMBER GENERATED  BY DEFAULT AS IDENTITY PRIMARY KEY,
  3    name VARCHAR2(100)
  4  );

Table created.

SQL> 

GENERATED ALWAYS：严格自增，适合无需手动干预的场景。
GENERATED BY DEFAULT：允许手动覆盖，适合需要灵活性的场景。