代碼如下(plsql)：

SQL> desc tb27_1

Name? Type? ? ? Nullable Default Comments?

----- --------- -------- ------- --------?

ID? ? NUMBER(3)? ? ? ? ? ? ? ? ? ? ? ? ? ?

GARDE NUMBER(3) Y? ? ?

//id是主鍵

SQL> select * from tb27_1? ;

? ID GARDE

---- -----

? ?1? ? ?2

? ?3? ? ?4

SQL> delete from tb27_1 where garde=2;

delete from tb27_1 where GRADE=2

ORA-00904: "GRADE": 標識符無效

SQL> delete from tb27_1 where id=1;

1 row deleted