Analytical Queries - Queries Across Time

The below query shows us favorite numbers shared by" zsmith and jdoe, using zmith's favorite numbers, as of block 8, and jdoe's favorite numbers, as of block 9.

{
  "select": "?nums",
  "where": [
    ["$fdb8", ["person/handle", "zsmith"], "person/favNums", "?nums"],
    ["$fdb9", ["person/handle", "jdoe"], "person/favNums", "?nums"]
  ]
}

Write a Query

Using the above query as an example, write a query that checks whether jdoe and zsmith had shared favorite artists (person/favArtists) when jdoe was at block 10, and when zsmith was at block 18.