Question

Ok, so I have 4 tables.

A users table with columns id and name.

A groups table with columns id, name and owner.

A items table with columns group and content.

A content table with columns id, name and duration.

Each user can have several groups. Each group can have several items inside it. Each item represents one of the pieces of content.

I want to be able to list all the groups, with a sum of all durations of each piece of content inside that group.

What Ive been trying is this:

select groups.id,groups.name,users.name,sum(content.duration) as duration from groups
join users on groups.owner=users.id
join items on items.group=groups.id
join content on content.id=items.content

Unfortunately this only gives me one result, with a total sum of all the durations of each piece of content in all of the groups – like so:

"g001", "Group 1", "Me", "400"

What I am expecting is something like:

"g001", "Group 1", "Me", "160"
"g002", "Group 2", "You", "160"
"g003", "Group 3", "Them", "80"

Answer 1

try this

   select groups.id,groups.name,users.name,sum(content.duration) as duration from groups
   join users on groups.owner=users.id
   join items on items.group=groups.id
   join content on content.id=items.content
   group by groups.name