Add Execute Raw SQL In An Ecto Migration as an elixir til

elixir/execute-raw-sql-in-an-ecto-migration.md

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+# Execute Raw SQL In An Ecto Migration
+
+If you are performing a database migration with
+[Ecto](https://hexdocs.pm/ecto/Ecto.html), perhaps the most straightforward
+approach is to use Ecto's DSL. However, the DSL may not always be the best
+choice. Being able to write raw SQL gives you more control. It will also
+enable you to use database features that may not be directly or easily
+available through the DSL.
+
+Raw SQL can be included in a Ecto migration with a combination of Elixir's
+heredoc syntax and the [`Ecto.Migration#execute/1`
+function](https://hexdocs.pm/ecto/Ecto.Migration.html#execute/1). You'll
+also need to provide both an `up` and `down` function to ensure that your
+migrations are reversible.
+
+```elixir
+defmodule MyApp.Repo.Migrations.CreatePostsTable do
+  use Ecto.Migration
+
+  def up do
+    execute """
+      create table posts (
+        id serial primary key,
+        title varchar not null,
+        body varchar not null default '',
+        inserted_at timestamptz not null default now(),
+        updated_at timestamptz not null default now()
+      );
+    """
+  end
+
+  def down do
+    execute "drop table posts;"
+  end
+end
+```