IBM created SQL in the 1970s as a language to query the relational database they had invented. Later, Oracle came to the market with PL/SQL in the 1980s, followed swiftly by T-SQL, which has been with us right since the Sybase SQL server days and now encompasses the SQL-92 ANSI standard. Thankfully Microsoft has again extended it for us in SQL Server 2012, adding new functionality as they see appropriate. While some think it is not acceptable to write non-standard SQL, remember that even simple DDL commands such as CREATE INDEX are an extension.
This means it is very easy to write non-standard SQL and that is no different to any of the other major database vendors. In fact, it contributes to driving future standards without which SQL would stagnate. But for us, it means a richer, easier to use language with features that would otherwise be difficult to implement, particularly from a performance perspective. Furthermore if we have no plans to port our applications to...