Question

This one is stumping me, I will just go ahead and explain via SQL. Here is the data structure:

Property

PropertyId     Name         
1              Property one
2              Property two

Property Features

PropertyFeatureId     FeatureId     PropertyId
1                     1             1
2                     2             1
3                     1             2

Feature

FeatureId     Name
1             Hot tub
2             Wifi

How would I go about finding all properties that have a hot tub AND wifi? So in the example above I would want propery 1, but not 2.

One way I suppose is inner-joining and filtering by the ones we want, but I want to generalize this so I can find all properties with feature A, B, C and so on.

Answer 1

The idea here is to count the number of instances of propertyName and that it is equal to the number of values supplied in the WHERE clause condition.

SELECT  a.Name
FROM    Property a
        INNER JOIN [Property Features] b
            ON a.PropertyID = b.PropertyId
        INNER JOIN Feature c
            ON b.FeatureID = c.FeatureID
WHERE   c.Name IN ('Hot tub','Wifi')
GROUP BY a.Name
HAVING COUNT(DISTINCT c.Name) = 2

SQLFiddle Demo