Decode statement

I have two tables, "A" is the items table that holds the details about an item and table "B" is the repair table that holds the details about the repairs performed on items in the table "A"

My goal is to select the details of an item based on the values supplied by the user for:

• a single owner or all owners
• a single owner and a single classification
• all owners and a single classification
• classification and no owner

So, my logic was to select the desired columns from table "A" where the ID for table "A" is found in table "B"