$select->where('field2 = ?', 'foo', Zend_Db::PARAM_STR);
This is not the type of values you are expected to provide here. $type,
in this case, is expected to be one of these:
Zend_Db::INT_TYPE, Zend_Db::BIGINT_TYPE, and Zend_Db::FLOAT_TYPE
As mentioned here in the quote() documentation:
http://framework.zend.com/manual/en/zend.db.adapter.html#zend.db.adapter.quoting.quote
The proper usage is more than likely not providing anything at all,
after all it works as expected like that right? :) The default is to
quote values.
BTW, what DB platform are you using?
-ralph