Open
Description
For a table that looks something like:
| filename | version | foo |
|---|
I am looking to write a query that returns, for each given filename, the row with greatest version for that filename.
Considering first the simple case of a query for a single filename, we can write:
selectLatest fname =
runSelectReturningOne
$ limit_ 1
$ orderBy_ (desc_ . (.version))
$ filter_ (Schema.File.name >>> (==. val_ fname))
$ all_ db.fileTableI am trying to adjust this to support multiple filenames:
selectLatest fnames =
runSelectReturningList do
-- for each filename in the given list..
fname <- values_ $ val_ <$> fnames
-- ..find the row with maximum version matching the filename.
limit_ 1
$ orderBy_ (desc_ . (.version))
$ filter_ (Schema.File.name >>> (==. val_ fname))
$ all_ db.fileTableHowever this results in a run-time error:
SqlError {sqlState = "42703", sqlExecStatus = FatalError, sqlErrorMsg = "column t0.res0 does not exist", sqlErrorDetail = "", sqlErrorHint = "There is a column named \"res0\" in table \"t0\", but it cannot be referenced from this part of the query."}