Specifically, if all the OR predicates in a WHERE clause are of the form
simple column reference = Expression
where the columnReference is the same for all predicates in the OR
chain, transforms the
OR chain into an IN list of the following form:
simple column reference IN (Expression1, Expression2, ..., ExpressionN)
The new predicate might be optimizable.
For example, can
transform the following statement:
SELECT * FROM Flights
WHERE flight_id = 'AA1111'
OR flight_id = 'US5555'
OR flight_id = ?
into this one:
SELECT * FROM Flights
WHERE flight_id IN ('AA1111', 'US5555', ?)
If this transformed IN list is a static IN list,
also performs the
static IN list transformation (see ).