根据参数指定的列名和值查询员工信息（使用动态sql语句）

create or replace procedure dyn_sql_test(p_col varchar2, p_value varchar2) as
  v_sal employees.salary%type;
  v_str varchar2(100);
begin
  v_str := 'select salary from employees where ' || p_col || ':= p_value';
  execute immediate v_str
    into v_sal
    using p _value;
  dbms_output.put_line(v_sal);
end dyn_sql_test;