create or replace procedure get_user_name( v_UserCode in char, v_UserName out char) is
begin
  select  DECODE (tu.username, 'NULL', '没有找到该读者', tu.username) into  v_UserName  from T_user  tu where tu.usercode = v_UserCode;
end get_user_name;

------解决方案--------------------

CREATE OR REPLACE PROCEDURE test
(in_code IN VARCHAR2,
out_code out varchar2
)
IS

BEGIN
   
  select name into  
         out_code
      from t_user
      where code=in_code  ;  
   


   
  EXCEPTION
    WHEN NO_DATA_FOUND THEN
      out_code:='没有找该读者';
    WHEN OTHERS THEN
      -- Consider logging the error and then re-raise
      RAISE;
END test;
/

------解决方案--------------------
out 参数要事先定义个变量的再传进去的
其实你这用自定义函数就行了

SQL code

CREATE OR REPLACE FUNCTIONtest 
(in_code  VARCHAR2, 

) 
RETURN varchar2
IS 
out_code  varchar2（100） ；

BEGIN 
    
   select name into  
          out_code 
       from t_user 
       where code=in_code  ;  
    


    return out_code;
   EXCEPTION 
     WHEN NO_DATA_FOUND THEN 
       return '没有找该读者'; 
     WHEN OTHERS THEN 
       -- Consider logging the error and then re-raise 
       RAISE; 
END test;