Why no language to replace SQL?

The history of programming is littered with programming languages. Some endure for ages (COBOL, C, Java) and some live briefly (Visual J++). We often develop new languages to replace existing ones (Perl, Python).

Yet one language has endured and has seen no replacements: SQL.

SQL, invented in the 1970s and popularized in the 1980s, has lived a good life with no apparent challengers.

It is an anomaly. Every language I can think of has a "challenger" language. FORTRAN was challenged by BASIC. BASIC was challenged by Pascal. C++ was challenged by Java; Java was challenged by C. Unix shell programming was challenged by AWK, which in turn was challenged by Perl, which in turn has been challenged by Python.

Yet there have been no (serious) challengers to SQL. Why not?

I can think of several reasons:

• Everyone loves SQL and no one wants to change it.
• Programmers think of SQL as a protocol (specialized for databases) and not a programming language. Therefore, they don't invent a new language to replace it.
• Programmers want to work on other things.
• The task is bigger than a programming language. Replacing SQL means designing the language, creating an interpreter (or compiler?), command-line tools (these are programmers, after all), bindings to other languages (Python, Ruby, and Perl at minimum), and data access routines. With all features of SQL, including triggers, access controls, transactions, and audit logs.
• SQL gets a lot of things right, and works.

I'm betting on the last. SQL, for all of its warts, is effective, efficient, and correct.

But perhaps there is a challenger to SQL: NoSQL.

In one sense, NoSQL is a replacement for SQL. But it is a replacement of more than the language -- it is a replacement of the notion of data structure. NoSQL "databases" store documents and photographs and other things, but they are rarely used to process transactions. NoSQL databases don't replace SQL databases, they complement them. (Some companies move existing data from SQL databases to NoSQL databases, but this is data that fits poorly in the relational structure. They move some of their data but not all of their data out of the SQL database. These companies are fixing a problem, not replacing the SQL language.)

NoSQL is a complement of SQL, not a replacement (and therefore not a true challenger). SQL handles part of our data storage and NoSQL handles a different part.

It seems that SQL will be with us for some time. It is tied to the notion of relational organization, which is a useful mechanism for storing and processing homogeneous data.