POPULATING DROPDOWN IN MY DATABASE USING PHP

COULD SOMEONE HELP ME ON HOW TO POPULATE MY DROPDOWN MENU USING MY DATABASE...
THE NAME OF MY TABLE IS APRILLE AND I WANT TO HAVE A TWO DROPDOWN MENU IN WHICH THE 2ND IS DEPENDENT ON THE FIRST CHOICE


DATABASE

TABLE NAME: APRILLE

CATEGORY SUBCATEGORY
ALPHABET A
ALPHABET B
ALPHABET C
NUMBERS 1
NUMBERS 2
NUMBERS 3

THE FIRST DROPDOWN IS THE CATEGORY AND THE SECOND IS SUBCATEGORY...
IF I CHOOSE ALPHABET ON THE FIRST DROPDOWN THE SECOND DROPDOWN CONTENTS WILL BE A, B, C AND SAME AS THROUGH WITH THE NUMBERS, IF I PICK NUMBERS IN THE 1ST DROPDOWN THE SECOND DROPDOWN WILL BE 1,2,3

THANX FOR ANY HELP...