Which RDBMS has the richest super-set of ANSI-SQL?

Back in 1989, when I used to program with Oracle 5.2.3 on UNIX and VAX/VMS platforms, I considered SQL*PLUS as having the richest super-set of built-in functions. ORACLE*FORMS also had the ability to embed SQL statements within triggers. That was then, 21 years ago. At present, which other RDBMS' have come close, have the same, or more functionality than Oracle's SQLPLUS, DB2?.. SQL-Server?.. T-SQL?.. MySQL?.. etc?

From stackoverflow

• It's hard to tell what is "richest". All systems have some proprietary things which the other systems don't support, including, but not limited to:

  • MODEL clause in Oracle
  • CROSS APPLY in SQL Server
  • DISTINCT ON in PostgreSQL
  • ON DUPLICATE KEY UPDATE in MySQL
  Frank Computer : @Quassnoi: OK, apart from those proprietary directives, which has the most comprehensive library of built-in functions, e.g. NVL(..), TODATE(..),SOUNDEX, DECODE, ENCRYPT, etc?

  Quassnoi : @Frank: I really don't know how to count this. In terms of "the maximal number of recognized built-in functions", most probably it will be `PostgreSQL`.

  Frank Computer : @Quassnoi: OK, not so much max, rather functionally useful!.. would you agree that Oracle was the pioneer in offering a robust super-set of SQL and continues to provide the richest set?

  Hao : @Frank Computer: "would you agree that Oracle was the pioneer in offering a robust super-set of SQL and continues to provide the richest set?" That question is now different from your original question "At present, which other RDBMS' have come close, have the same, or more functionality than Oracle's SQLPLUS?". That makes the original question a very subjective one

• DB2 has a complete Java virtual machine available for server side processing stored procedures, you don't get much more "complete" than that.

  CouchDB uses JavaScript, can't get much more flexible and complete that that either.