Oracle creates a stored procedure successfully, but the compilation fails

The initial code is ：

CREATE   or   REPLACE    PROCEDURE   get_department_name
(in_empno   IN   number(4)  ,   out_department_name     OUT   varchar2)  IS
BEGIN
    SELECT    d.dname
    INTO         out_department_name
    FROM       emp e    LEFT   JOIN  dept d on e.deptno=d.deptno
    WHERE    e.empno=in_empno;
END;

However, an exception is reported ：

solve ： The input parameter in_empno The data type of is changed to number, When creating a stored procedure , Numeric types can only be used NUMBER, Length cannot be specified .

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in addition ： The exception shows that the stored procedure was created successfully , And in Plsql Success is also shown in , In fact, it is equivalent to not creating successfully , Cannot call at all , The following exception is reported when calling

At first, I thought that although the compilation was wrong , But after all, it was created successfully , It should work , The result is that... Cannot be called at all . All exceptions with errors if the report is created successfully , Be sure to get rid of this exception , Otherwise, the stored procedure is not created .