Oracle is a classic case where being first was everything. In Oracle's case, being first in number of databases sold. I am on a new project in an 'enteprisey'

Oracle is a classic case where being first was everything. In Oracle's case, being first in number of databases sold. I am on a new project in an 'enteprisey' environment and a decision was made to use Oracle database simply because that's what most people know. Oracle became dominant (for a generation) -> lot's of dba's learned Oracle -> now many (in 2011) still choose it because that's all they know.