Non-SQL Databases
Another solution is to use an object-oriented database management system (OODBMS) or document-oriented databases such as native XML databases. OODBMSs are databases designed specifically for working with object-oriented values. Using an OODBMS eliminates the need for converting data to and from its SQL form, as the data is stored in its original object representation and relationships are directly represented, rather than requiring join tables/operations.
Document oriented databases also prevent the user from having to "shred" objects into table rows. Many of these systems also support the XQuery query language to retrieve datasets.
Object-oriented databases tend to be used in complex, niche applications. One of the arguments against using an OODBMS is that switching from an SQL DBMS to a purely object-oriented DBMS means that you may lose the capability to create application independent queries for retrieving ad-hoc combinations of data without restriction to access path. For this reason, many programmers find themselves more at home with an object-SQL mapping system, even though most object-oriented databases are able to process SQL queries to a limited extent.
Read more about this topic: Object-relational Mapping