21: Querying graph relations

Querying a relation is usually done using the same arrow syntax used in the RELATE statement to create it.

Here is a query on a single person record which returns its name as well as the path ->works_at->place. The graph query checks to see if the person is linked to the works_at table (the in field, because the arrow at ->works_at is going in to works_at) and if there is a place at the other end (the out field, because the arrow at works_at->place goes out from works_at and looks for a place record at that point).

SELECT 
    name, 
    ->works_at->place
FROM person LIMIT 1;

Run Query

[
  {
    "->works_at": {
      "->place": [
        place:surreal_library
      ]
    },
    name: 'Lydia Wyndham'
  }
]

Since the place point in the query will look for place records, the .{} destructuring operator can be used to access the fields, such as name and address. We will also give it the alias workplace for readability, and remove the LIMIT to show all the person records.

SELECT 
    name, 
    ->works_at->place.{ 
    name, 
    address
  } AS workplace
FROM person;

Run Query

[
  {
    name: 'Sara Bellum',
    workplace: [
      {
        address: '2025 Statement Street, Riverdale',
        name: 'Surreal Library'
      }
    ]
  },
  {
    name: 'Lydia Wyndham',
    workplace: [
      {
        address: '2025 Statement Street, Riverdale',
        name: 'Surreal Library'
      }
    ]
  },
  {
    name: 'Samm Schwartz',
    workplace: [
      {
        address: '2025 Statement Street, Riverdale',
        name: 'Surreal Library'
      }
    ]
  }
]

You can also use a graph query directly on a record instead of using a SELECT statement.

-- Get Samm's record ID
LET $samm = SELECT id FROM ONLY person WHERE name = 'Samm Schwartz' LIMIT 1;

-- Then just query from the record ID, no SELECT
$samm->works_at->place.{ address, floors, name };

Run Query

[
  {
    address: '2025 Statement Street, Riverdale',
    floors: 8,
    name: 'Surreal Library'
  }
]

Turning the -> arrow around to <- makes a graph query in the other direction. From the point of view of the place record, there is no ->works_at->person path because it's not the place that works at the person, it's the person that works at the place. Turning the arrows around will accomplish this.

The relation is still visually easy to follow, because place<-works_at<-person still shows that person leads into works_at and then into place. The only difference is that place is being used as the starting point now.

place:surreal_library<-works_at<-person.name;

Run Query

Output: the names of the people that work at the library.

[
  'Samm Schwartz',
  'Sara Bellum',
  'Lydia Wyndham'
]