feat(ecto-adapter): implement query_many/4 (#65)

This enables a multi-statement query, e.g. "select 1; select 2".

lib/snowflex/connection.ex

@@ -297,6 +297,9 @@ defmodule Snowflex.Connection do
     %Result{num_rows: count, success: true, statement: query.statement}
   end
 
+  defp parse_result(results, query) when is_list(results),
+    do: Enum.map(results, fn result -> parse_result(result, query) end)
+
   defp parse_result(result, _query), do: result
 
   defp parse_result(columns, rows, query) do

lib/snowflex/ecto/connection.ex

@@ -20,9 +20,26 @@ defmodule Snowflex.EctoAdapter.Connection do
     Snowflex.query(conn, sql, params, opts)
   end
 
+  def query_many!(conn, sql, params, opts) do
+    case query_many(conn, sql, params, opts) do
+      {:ok, result} -> result
+      {:error, error} -> raise error
+    end
+  end
+
   @impl true
-  def query_many(_conn, _sql, _params, _opts) do
-    raise "query_many is not supported by Snowflake"
+  @doc """
+  Run a multi-statement query.
+
+  The `MULTI_STATEMENT_COUNT` Snowflake parameter must be set to 0 to allow
+  multi-statement queries.
+
+  https://docs.snowflake.com/en/sql-reference/parameters.html#multi-statement-count
+  """
+  def query_many(conn, sql, params, opts) do
+    with {:ok, result} <- query(conn, sql, params, opts) do
+      {:ok, List.wrap(result)}
+    end
   end
 
   @impl true