Issue in SQL Query while using “or” condition

Hi,
I have created a 3 SQL tables. The table details are as follows,
Table Fields
Food_Item Food_Item_id, Food_Item_name, item_category_id
Food_item_category Food_item_id, Food_item_name
Food_item_order Food_item_id, item_id, item_category_id
I tried to search for all food_item_id in Food_item_order table where few rows have item_id and item_category_id as null. Some rows have the combination of item_category_id and item_id as null. I tried to get all of the items that are null by item_category_id from the table. I have used “OR” condition in the SQL query, but it seems that it doesn’t produce the expected result. Can someone help me modify this query to produce the exact result? Thanks.
