How can I see the raw SQL generated for an Ecto.Query?

Question

I have an Ecto.Query and a Repo, such that I can call Repo.all(query) and get results. However, the results are not what I expect.

Answer 1

You can use Ecto.Adapters.SQL.to_sql/3:

iex> Ecto.Adapters.SQL.to_sql(:all, Repo, Post)
{"SELECT p.id, p.title, p.inserted_at, p.created_at FROM posts as p", []}

This function is also available under the repository with name to_sql if you’re using a SQL based adapter:

 iex> Repo.to_sql(:all, Post)
  {"SELECT p.id, p.title, p.inserted_at, p.created_at FROM posts as p", []}

The query can be any struct that implements the Ecto.Queryable protocol like Post above(which is a module that imports Ecto.Schema). An Ecto.Query can also be passed:

iex> query = Ecto.Query.where(Post, [p], p.views > 10)
iex> Ecto.Adapters.SQL.to_sql(:all, Repo, query)
{"SELECT p.id, p.title, p.inserted_at, p.created_at FROM posts as p WHERE p.views > $1", [10]}