From Eigenpedia

This page describes some deviations we're considering from SQL:2003 for cases where the specification is either completely counterintuitive, exceedingly pedantic, or backwards-incompatible. As part of implementing these, we should first implement a strict mode which disables them (different Eigenbase packagings may use different default modes; the vanilla distribution should default to strict).

• Aggregated type of character literals
• Concatenation of non-character items
• ORDER BY column ordinal as a literal integer (deleted in SQL:1999 to avoid ambiguity in ORDER-BY-expression, but since this has been in SQL since the beginning, seems like a mistake, especially since no one would intentionally ORDER BY a constant, would they?)
• Comparisons for non-standard types BINARY and VARBINARY
• SYSTEM DEFINED JAVA calling convention for FarragoUdx
• uncasted nulls passed as arguments to routine invocations (eigenjira:FRG-128)
• GROUP BY expression
• type derivation rules for precision and scale of fixed-point numeric operation results (see NumericType for details)

Items below are extensions which have been suggested:

• allow TRIM('ab' from 'abcde'); SQL:2003 only allows single-character trim strings (dtbug 154)
• allow implicit numeric cast in UDR arguments (eigenjira:FRG-330)

Items below are choices made for behaviors which the standard specifies as implementation-defined:

• In case of loss of trailing digits (e.g. Part 2 Section 6.26 General Rule 5.b), use rounding instead of truncation.

Items below are currently being worked out:

• interval operators

SQL:2008

We can also check later versions of the standard for guidance:

• http://iablog.sybase.com/paulley/2008/07/sql2008-now-an-approved-iso-international-standard/
• http://www.wiscorp.com/SQLStandards.html

LucidDB Personality

See also LucidDbSqlConformance, some of which overlaps with the items above, but some of which is specific to LucidDB.