Improve note about unique index and foreign key on has_one association

Related to f1af967e0055a33c45071848a049ff342e9c291e. [ci skip]

1 files changed, 7 insertions, 6 deletions

diff --git a/guides/source/association_basics.md b/guides/source/association_basics.md
index 498bc449d2..abac54d22d 100644
--- a/guides/source/association_basics.md
+++ b/guides/source/association_basics.md
@@ -146,14 +146,15 @@ class CreateSuppliers < ActiveRecord::Migration
 end
 ```
 
-If you happen to want to create a unique index with foreign key constraint...
-Then I would suggest using this for creating the accounts table instead:
+Depending on the use case, you might also need to create a unique index and/or
+a foreign key constraint on the supplier column for the accounts table. In this
+case, the column definition might look like this:
 
 ```ruby
-  create_table :accounts do |t|
-    t.belongs_to :supplier, index: true, unique: true, foreign_key: true
-    # ...
-  end
+create_table :accounts do |t|
+  t.belongs_to :supplier, index: true, unique: true, foreign_key: true
+  # ...
+end
 ```
 
 ### The `has_many` Association