Fix: Missing uniqueness constraint for projects.identifier in the database (#41975).

Patch by Hiroyuki Kano (user:hiropk).


git-svn-id: https://svn.redmine.org/redmine/trunk@23407 e93f8b46-1217-0410-a6f0-8f06a7374b81

db/migrate/20241213003659_add_unique_index_to_projects_identifier.rb

@@ -0,0 +1,5 @@
+class AddUniqueIndexToProjectsIdentifier < ActiveRecord::Migration[7.2]
+  def change
+    add_index :projects, :identifier, :unique => true
+  end
+end