How i can select one column form one table to another??

I am using Sqlite Database in android. I created one table named Add_Category and column name in this table are KEY_ID, KEY_CATEGORY_NAME and KEY_CATEGORY_DESCRIPTION. and Another table named Income and column name in this table are KEY_ID, KEY_AMOUNT, KEY_DATE, KEY_CATEGORY_NAME. In Table Add_category, user will add category in database. and I want to retrive that category name at KEY_CATEGORY_NAME OF TABLE INCOME FROM database. so what should i do ??? plz help me..