Add SQL constraint to ensure unicity of emails

Author: Wardormeur

scripts/database/pg/migrations/025.do.make-email-unique.sql

@@ -0,0 +1,10 @@
+DO $$
+  BEGIN
+    BEGIN
+      CREATE UNIQUE INDEX sys_user_unique_email ON sys_user(email) WHERE email != '';
+    END;
+    BEGIN
+      CREATE UNIQUE INDEX cd_profiles_unique_email ON cd_profiles(email) WHERE email != '';
+    END;
+  END;
+$$