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Comment by 1st1 | Hacker News Reader

You do joins when you traverse schema type paths in EdgeQL, it's just that the actual joins are implicit (well, compared to SQL):

  SELECT User {
    email,
    preferences: {
      name,
      value
    }
  } FILTER .id = '...'

E.g. in the above example we'd join the underlying User and Preferences tables for you.

You can also do cross joins and all other funky stuff.

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How would you represent a self join?

If given a recursive schema like this:

    type Tree {
        property value -> str
        link parent -> Tree
    }

you'd traverse the link as usual:

    SELECT Tree {
        value,
        parent: {
            value
        }
    }
    FILTER .parent.parent.parent.value = 'foo'

If there's a need to self-join on an arbitrary property, then you could use a `WITH` clause to explicitly bind the two sets:

    WITH
        T1 := Tree,
        T2 := Tree
    SELECT
        T1 {
            similarly_valued := (SELECT T2 FILTER T1.value = T2.value)
        }

Thanks!

Example from the cheatsheet:

``` WITH P := Person SELECT Person { id, full_name, same_last_name := ( SELECT P { id, full_name, } FILTER # same last name P.last_name = Person.last_name AND # not the same person P != Person ), } FILTER EXISTS .same_last_name ```

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