Btw if you are dealing with datetime, please check out these before investing unnecessary time into fragments() like I did

https://hexdocs.pm/ecto/Ecto.Query.API.html#from_now/2

• Aggregates: count/0, count/1, avg/1, sum/1, min/1, max/1
• Date/time intervals: datetime_add/3, date_add/3, from_now/2, ago/2

Intervals

Ecto supports following values for interval option: "year", "month", "week", "day", "hour", "minute", "second", "millisecond", and "microsecond".

Date/Time functions like datetime_add/3, date_add/3, from_now/2, ago/2 take interval as an argument.

All of these will execute on the SQL server and use the native underlying functions

I’m not going to answer your question again

In the sample above, I’d personally opt to “inject” the empty slot once the results have come back from the database. Adding to the front of a list in Elixir is a very “cheap” operation.

e.g.

  slots = [%{slot: ~D[<whatever date>]} | Repo.all(more_basic_query)]

I suspect the situation you are asking about (effectively “UNION”-ing a hand crafted row of data with database results) doesn’t fit within the Ecto model. I had another look through the documentation and I can’t see anything that comes close. So you will either need to use a fragment, or go for the option I noted above, or build a view that performs the UNION on the database side.

This can be done but its hacky. However, IMO it should not be removed (PLEASE DONT REMOVE THIS we want the query scrubbed without the FROM condition) taking from SQL injection you can use -- to rem out the FROM condition.

MyRepo.all(
      from(d in "_",
        select: %{
          test: fragment("to_timestamp('11:12:02.020.001230', 'HH:MI:SS.MS.US') as slot--")
        }
      )
    )

sure you can but haven’t tested nested, inner queries but cast and rest can be done.

def update_title(post, new_title) do
  query =
    from "posts",
      where: [id: ^post.id],
      update: [set: [title: ^new_title]]

  MyApp.Repo.update_all(query, [])
end

More examples can be found at

https://hexdocs.pm/ecto/schemaless-queries.html

https://hexdocs.pm/ecto_sql/Ecto.Adapters.SQL.html#query/4

Ecto.Adapters.SQL.query(MyRepo, "SELECT $1::integer + $2", [40, 2])
{:ok, %{rows: [[42]], num_rows: 1}}