Do you any of you know if there is a direct connection between the cost of a RDBMS and their compliance to a SQL standard? I know there are some free ones out there but also know there are many that charge for it.
I believe that there isn't connection between those things; all (I guess ...) RDBMS's more or less follow SQL standards, and - in addtion - have some special features, or - in some releases - don't support some standard solutions. For example, Oracle 7 doesn't know OUTER JOIN, but supports it through the "(+)" operator.
Besides, even the most expensive RDBMS's have free versions - Oracle XE is one of them; Microsoft SQL Server also has its free version (at least, I *think* I saw it distributed on CD's attached to a computer magazine recently, but can't remember its name - will check and post it here later).
"Microsoft SQL Server Express Edition"; who would tell - the same name as the Oracle XE stands for