I would like to implement a query that search on a set of table for all
records that have some keyword on their field.
This query must implement the "simple search" function by keywords on a
website (I mean...user insert a keyword in the search box and all the
entities in the Db with a coloumn hat contains that keywords must return).
I would like to know what is the best way to implement the search on a
webisite db (or a subset of tables) or if there is already some
eclipselink facility to get that.
Are you trying to query a single class, or multiple classes?
If you are trying to query multiple class, you may need to query them one by one based on your model.
One possibility may be to use EclipseLink's interface descriptor support if all of your class share a common interface. Then you could perform a single conceptual query, and EclipseLink would query each table. JPA does not support interfaces, so you would need to define the interface descriptors using a SessionCustomizer and the EclipseLink descriptor code API.