Sequel.migration do
  change do
    alter_table(:testset) do
      add_foreign_key :database_uuid, :databases, type: :uuid
    end
  end
end

Sequel.migration do
  change do
    create_table(:testset) do
      serial :set, primary_key: true
      text :info, unique: true, null: false
      text :testdb, null: false
      text :testuser, null: false
      text :testhost, null: false
      text :testport, null: false
      text :settings
      foreign_key :database_uuid, :databases, type: :uuid
    end
  end
end
--- 
+++ 
@@ -1,14 +1,7 @@
 Sequel.migration do
   change do
-    create_table(:testset) do
-      serial :set, primary_key: true
-      text :info, unique: true, null: false
-      text :testdb, null: false
-      text :testuser, null: false
-      text :testhost, null: false
-      text :testport, null: false
-      text :settings
-      foreign_key :database_uuid, :databases, type: :uuid
+    alter_table(:testset) do
+      add_foreign_key :database_uuid, :databases, type: :uuid
     end
   end
 end
Change testset migration to alter table not create it

The testset migration should not create the lone testset table, but it
should alter the one created by resultsdb.sql, at least until all of
resultsdb.sql is included in the migrations.
