relational-division

Suppose it's a website that sells photo cameras. Here are my entities (tables): Camera: A simple camera Feature: A feature like: 6mp, max resolution 1024x768, The thing is between cameras and feature i've got a Many to Many relationship, so i have an extra table: camera -> cameras_features -> feature So, the query is simple: How to get all the cameras that have the feature 1,2 and 3? It's like constructing a bitmap index. Data you can use to test if the solution is ok C1 has features 1,2,3 C2 has features 1,2,4 C3 has features 1,2 Here are querys and the expected result: Show all the cameras

I could not get a hint on how to write SQL queries for A and B for the following schema. Programme (Pid:int, Department:string...) Employee (Eid:int, Department:string..) Participation (Pid:int, Eid:int, ..) A. Names of programmes participated by all employees B. Names of employees participating in all his department's programmes. Any guidelines would be helpful. Haven't tried these, but this is what I would be thinking: SELECT pg.Name FROM Participation AS p INNER JOIN Programme AS pg ON p.Pid = pg.Pid GROUP BY p.Pid HAVING COUNT(*) = (SELECT COUNT(*) FROM Employeee) SELECT e.Name FROM

I'm creating a simple filtering system for my website. I have a many to many relationship between venues and amenities. Here are my tables. NOTE: all ids are uuids. Making them short for simplicity venues: | id | name | _________________________ | 'aaa' | 'first venue' | | 'bbb' | 'second venue' | | 'ccc' | 'third venue' | amenities: | id | name | ___________________________ | 'aaa' | 'first amenity' | | 'bbb' | 'second amenity' | | 'ccc' | 'third amenity' | amenity_venue: | amenity_id | venue_id | ______________________________ | 'aaa' | 'aaa' | | 'bbb' | 'aaa' | | 'ccc' | 'aaa' | | 'aaa' |

I have separate sets of "classes" and "groups", each of which has been assigned one or more tags. I would like to find, for each group, the subset of classes that contains the same (or more) tags for each group. Some sample data: declare @Groups table ( GroupID int, TagID int ) insert @Groups values (1,1),(1,2),(1,3), (2,1),(2,2), (3,1),(3,2),(3,3),(3,4) declare @Classes table ( ClassID int, TagID int ) insert @Classes values (1,1),(1,2), (2,1),(2,2), (3,1),(3,2),(3,3) select * from @Groups select * from @Classes And output: GroupID TagID 1 1 1 2 1 3 2 1 2 2 3 1 3 2 3 3 3 4 ClassID TagID 1 1 1

So imagine that you have a table of Products (ID int, Name nvarchar(200)) , and two other tables, ProductsCategories (ProductID int, CategoryID int) and InvoiceProducts (InvoiceID int, ProductID int) . I need to write a query to produce a set of products that match a given set of invoice ids and category ids such that the list of products match all the specified categories and all the specified invoices, without falling back to dynamic SQL. Imagine I need to find a list of products that are in both categories 1 and 2 and in invoices 3 and 4. As a start, I've written a stored-procedure that