具有内联PL/SQL函数的Oracle 12c-SQL查询

WITH 
    FUNCTION get_number RETURN NUMBER IS
    BEGIN
        RETURN 12345;
    END;
    
SELECT employee_id, first_name, last_name, get_number()
FROM hr.employees

ORA-00905: missing keyword
Invalid statement
ORA-00904: "GET_NUMBER": invalid identifier

SQL> WITH
  2      FUNCTION get_number RETURN NUMBER IS
  3      BEGIN
  4          RETURN 12345;
  5      END;
  6  SELECT employee_id, first_name, last_name, get_number()
  7  FROM hr.employees;
  8  /

EMPLOYEE_ID FIRST_NAME           LAST_NAME                 GET_NUMBER()
----------- -------------------- ------------------------- ------------
        100 Steven               King                             12345
        101 Neena                Kochhar                          12345
        102 Lex                  De Haan                          12345
        103 Alexander            Hunold                           12345
        104 Bruce                Ernst                            12345
        105 David                Austin                           12345
        106 Valli                Pataballa                        12345
...

SQL> WITH
  2      FUNCTION get_number RETURN NUMBER IS
  3      BEGIN
  4          RETURN 12345;
    FUNCTION get_number RETURN NUMBER IS
             *
ERROR at line 2:
ORA-00905: missing keyword


SQL>     END;
SP2-0042: unknown command "END" - rest of line ignored.
SQL> SELECT employee_id, first_name, last_name, get_number()
  2  FROM hr.employees;
SELECT employee_id, first_name, last_name, get_number()
                                           *
ERROR at line 1:
ORA-00904: "GET_NUMBER": invalid identifier