How to achieve the querys in one statement

Question

<p>
Hi,everyone:
I have a table:
create table my_cube
(model char(10), theyear char(10), color char(10), units_sold smallint);
</p>
<p>
To list the unit-sold percentage of the 'chevy' model in 1990, i write:
</p>
<p>
select 1990, 'Chevy', round(( (select sum(units_sold) from my_cube where model='Chevy' and theyear=1990)/(select sum(units_sold) from my_cube where theyear=1990) )*100, 2) from dual;
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<p>
But i'm wondering is that possible to list all the unit-sold percentage of all models in every year in one statement? Could anyone help me. Thanks.
</p>
<p>
Here are some values for test:
insert into my_cube values('Chevy', 1990, 'Red', 5);
insert into my_cube values('Chevy', 1990, 'White', 87);
insert into my_cube values('Chevy', 1990, 'Blue', 12);
insert into my_cube values('Chevy', 1991, 'Red', 54);
insert into my_cube values('Chevy', 1991, 'White', 95);
insert into my_cube values('Chevy', 1991, 'Blue', 19);
insert into my_cube values('Chevy', 1992, 'Red', 31);
insert into my_cube values('Chevy', 1992, 'White', 54);
insert into my_cube values('Chevy', 1992, 'Blue', 11);
insert into my_cube values('Ford', 1990, 'Red', 64);
insert into my_cube values('Ford', 1990, 'White', 62);
insert into my_cube values('Ford', 1990, 'Blue', 13);
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Answer 1

First of all, don't use CHAR. Use VARCHAR2. Save yourself some headaches.
Make the year column a number, and be careful about the column name MODEL. It's a reserved word.
Aside from the above solution, you could also use the handy ratio_to_report function:
SQL> select m_year, m_model
  2        ,sum(m_units_sold)
  3        ,ratio_to_report(sum(m_units_sold)) over (partition by m_year) r
  4  from   my_cube
  5  group  by m_year, m_model
  6  ;
              M_YEAR M_MODEL       SUM(M_UNITS_SOLD)                    R
                1990 Chevy                       104 .4279835390946502058
                1990 Ford                        139 .5720164609053497942
                1991 Chevy                       168                    1
                1992 Chevy                        96                    1