PL/SQL is Oracle's block structured programming language with direct support for SQL (StructuredQueryLanguage) objects. It is not dissimilar to the AdaLanguage. A StarUnit port is available for unit testing, see PlSqlUnit for a description.
The name PL/SQL is an obvious play on PL/I (PliLanguage). IBM may have trademarked all the numbers, but they apparently didn't have time to trademark the letters as well.