Question

I have the following tables:

list

• id – key
• name

item

• id – key
• name

list_item

• list_id – foreign key to list table
• item_id – foreign key to item table

I have the following query:

SELECT l.id, l.name
FROM list l, list_item li
WHERE l.id = li.list_id

I want to add to the result set, the count of items in the list. How do I do this?

Answer 1

SELECT l.id, l.name, COUNT(li.item_id) AS item_count 
FROM list l
LEFT JOIN list_item ON l.id = li.list_id
GROUP BY l.id