Starting with the standard, we will find that the SQL standard has four
levels:

o Entry-level: This is the level to which most vendors have complied. This
level is a minor enhancement of the predecessor standard, SQL/89. No database
vendors have been certified higher and in fact the National Institute of
Standards and Technology (NIST), the agency that used to certify for
SQL-compliance, does not even certify anymore. I was part of the team that got
Oracle7.0 NIST-certified for SQL/92 entry-level compliance in 1993. An entry
level compliant database has the feature set of Oracle7.0.

o Transitional: This is approximately 'halfway' between entry-level and
intermediate-level as far as a feature set goes.

o Intermediate: this adds many features including (not by any means an
exhaustive list):
Dynamic SQL
Cascade DELETE for referential integrity
DATE and TIME data types
Domains
Variable length character strings
A CASE expression
CAST functions between data types

o Full: Adds provisions for (again, not exhaustive):
Connection management
A BIT string data type
Deferrable integrity constraints
Derived tables in the FROM clause
Sub-queries in CHECK clauses
Temporary tables

The entry-level standard does not include features such as outer joins, the new
inner join syntax, and so on. Transitional does specify outer join syntax and
inner join syntax. Intermediate adds more, and Full is, of course all of SQL/92.

Most books on SQL do not differentiate between the various levels leading to
confusion on the subject. They demonstrate what a theoretical database
implementing SQL FULL would look like. It makes it impossible to pick up a
SQL book, and apply what you see in the book to just any SQL database. For
example, in SQL Server the 'inner join' syntax is supported in SQL statements,
whereas in Oracle8i it is not (but 9i does). Then again, Oracle7 supports
derived tables in the FROM clause (inline views) which is part of FULL but
others do not.

But, they are both SQL-compliant databases. You can do inner joins and outer
joins in Oracle, you will just do it differently than in SQL Server. The bottom
line is that SQL will not go very far at the entry-level.

All databases implement many of the features of the higher levels but do not
fully comply with the higher levels.


Now, as to how to do your statement above, either:

select sum( case when bsis = b then PROJMARCH+PROJJAN+PROJFEB
else 0
end ) as q1,
projyear
from ....


or more simply:

select sum( decode( bsis, b, PROJMARCH+PROJJAN+PROJFEB, 0 ) ) as q1,
projyear
...


if the issue is "well that makes my application Oracle dependent" -- use the CASE (thats ANSI) or use a view (best approach) and just port the views.