Stata : distinct values, count and histogram - stata

Question

I am new to Stata and still learning.
I have a var shaped like that :
+-------+
| Phase |
+-------+
| I |
+-------+
| I |
+-------+
| II |
+-------+
| III |
+-------+
| II |
+-------+
My goal is to draw a histogram with the possible value (I,II,III) (x-axis) and the number of each (2,2,1) (y-axis).
I though I could make a loop and store the number of each possible in an array but arrays does not seem to be implemented in Stata.
Is the any kind of function that do what I want already implemented or I have to write a function to distinct the value, then count them, then draw the histogram ?
Thank you.
/edit :
processed.p |
hase | Freq. Percent Cum.
------------+-----------------------------------
I | 266 0.92 0.92
I/II | 1,006 3.50 4.42
II | 10,867 37.76 42.18
II/III | 344 1.20 43.37
III | 9,248 32.13 75.51
IV | 6,984 24.27 99.77
NA | 65 0.23 100.00
------------+-----------------------------------
Total | 28,780 100.00
I found a way of counting distinct values.

Answer 1

I found the solution :
tab processedphase, matcell(x)
in order to obtain
processed.p |
hase | Freq. Percent Cum.
------------+-----------------------------------
I | 266 0.92 0.92
I/II | 1,006 3.50 4.42
II | 10,867 37.76 42.18
II/III | 344 1.20 43.37
III | 9,248 32.13 75.51
IV | 6,984 24.27 99.77
NA | 65 0.23 100.00
------------+-----------------------------------
Total | 28,780 100.00
then :
matrix list x
svmat x