diff options
Diffstat (limited to 'guides')
| -rw-r--r-- | guides/source/active_record_validations.md | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/guides/source/active_record_validations.md b/guides/source/active_record_validations.md index 93f76d3bf7..de26a9bd6d 100644 --- a/guides/source/active_record_validations.md +++ b/guides/source/active_record_validations.md @@ -606,9 +606,7 @@ This helper validates that the attribute's value is unique right before the object gets saved. It does not create a uniqueness constraint in the database, so it may happen that two different database connections create two records with the same value for a column that you intend to be unique. To avoid that, -you must create a unique index on both columns in your database. See -[the MySQL manual](http://dev.mysql.com/doc/refman/5.6/en/multiple-column-indexes.html) -for more details about multiple column indexes. +you must create a unique index on that column in your database. ```ruby class Account < ActiveRecord::Base @@ -628,6 +626,7 @@ class Holiday < ActiveRecord::Base message: "should happen once per year" } end ``` +Should you wish to create a database constraint to prevent possible violations of a uniqueness validation using the `:scope` option, you must create a unique index on both columns in your database. See [the MySQL manual](http://dev.mysql.com/doc/refman/5.6/en/multiple-column-indexes.html) for more details about multiple column indexes or [the PostgreSQL manual](http://www.postgresql.org/docs/9.4/static/ddl-constraints.html) for examples of unique constraints that refer to a group of columns. There is also a `:case_sensitive` option that you can use to define whether the uniqueness constraint will be case sensitive or not. This option defaults to |