You can of course write one-off code in Exchange Web Services to accomplish a specific task – but why reinvent the wheel? Sumatra has been inserting calendar, contact, and task items into Exchange from legacy systems for the last fourteen years. We’ve created a tool-set that allows you to read data from your SQL databases and insert them into Exchange.
Most of our users of this feature are using Oracle as the SQL of choice, but there's nothing specific to that vendor.
We call this the Sumatra Calendar Pump or just the "Pump" if you hear us referring to it in casual conversation.