create or replace function test
return varchar2
is
beginreturn 'hello world';
end test;
-- 函数调用
begindbms_output.put_line(test());
end

create or replace function get_name(v_id number
)
return varchar2
is --is类似于declarev_name varchar2(50);
beginselect username into v_name from person where id = v_id;return v_name;
end get_name;
-- 函数调用
begin dbms_output.put_line(get_name(1));
end;

create or replace function get_perons_info(f_id number,f_age out number
)
return varchar2
isv_name varchar2(50); --必须有声明长度
beginselect username, age into v_name, f_age from person where id = f_id;return v_name;
end get_perons_info;
-- 函数调用
declarev_age number;v_name varchar2(255);
beginv_name := get_perons_info(1, v_age );dbms_output.put_line('name:'||v_name||' age:'||v_age);
end;

create or replace function get_person_info2(f_id in out number
)
return varchar2
isv_name varchar2(50);
beginselect username, age into v_name, f_id from person where id = f_id;return v_name;
end get_person_info2;
-- 函数调用
declarev_id    number;v_name varchar2(50);
beginv_id := 1;v_name := get_person_info2(v_id);dbms_output.put_line('name:'||v_name||' age:'||v_id );
end;

create or replace function get_person_allreturn sys_refcursor
isp_cursor sys_refcursor;
beginopen p_cursor forselect *  from person;  return p_cursor;exceptionwhen others thenDBMS_OUTPUT.PUT_LINE('获取信息发生错误');
end get_person_all;
--函数调用
declarec_cursor sys_refcursor;r_person person%rowtype;
beginc_cursor := get_person_all();--2、打开游标
--  open c_cursor; --此处不需要显示地打开游标，因为调用存储过程的时候返回的游标已经打开了--3、提取数据loopfetch c_cursor into r_person;exit when c_cursor%notfound; -- 下面没有数据的时候，退出dbms_output.put_line('id:'||r_person.id);dbms_output.put_line('username:'||r_person.username);dbms_output.put_line('age:'||r_person.age); end loop;
end;

alter function 函数名称 compile; 

drop function 函数名称;

select * from dba_objects where object_name = '函数名称（字母大写）' and object_type ='FUNCTION';