Oracle support for hierarchical queries

Most of us already encountered the problem of walking through a tree-like structure in database table. Imagine a PERSON table with parent-child relationship, and we want to retrieve all descendants of a person quickly. In plain JDBC and standard SQL, you'll need to write yourself a recursive function and perform multiple requests on your favorite database. Good news for users of Oracle 10g databases: Oracle SQL has extensions to fetch all descendants in one single query! You just need to use the START WITH and CONNECT BY keywords. Have a quick look at this Oracle article for more details.

Thanks to ITwise and DbMotive for the great tip!