Language and development rules: Difference between revisions

Sometimes, we need another unique keys than primary key. We can add in this case an alternate unique key. When we need this, we can create an alternate unique key. Such an index is called by a name that start by prefix <tt>uk_</tt> followed by an underscore, then the the table name (this is required to avoid duplicate names of unique keys that may create problems for some DBMS like Postgresql) and then another string to define the key (this is to allow to have several unique keys on same table).