ZF-6565: Zend_Db should implement the REPLACE INTO extension with a replaceInto() function
MySQLs proprietary REPLACE INTO syntax is a useful one allowing elegant code in certain circumstances.
This attempts to deletes the row, and then performs an insert. Implementing it in Zend_Db would allow users of other RDMS brands to use this also; I see this as akin to Dojo's philosophy of smoothing out differences between browsers by providing a standard interface to them.
Implementing the ON DUPLICATE UPDATE functionality as outlined in ZF-266 (attempting the insert and then performing an update on exception) would also be a good solution