Limitations with AND & OR operators.

[SajadKarim]

Current implementation does not allow to form the following queries;

1. SELECT _id, "city", "customerid", "state", "firstname", "lastname", "zip", "address", "email" FROM "namespace_customersTable" WHERE ( ("customerid" = 3 AND "zip" = 22121) OR ( "customerid" = 1 AND "zip" = 22902 );
2. SELECT _id, "city", "customerid", "state", "firstname", "lastname", "zip", "address", "email" FROM "namespace_customersTable" WHERE ( ("customerid" = 3 OR "zip" = 22121) AND ( "customerid" = 1 OR "zip" = 22902 );

Table can be found at this link: https://github.com/SajadKarim/julea/blob/7e2768ce2cc7ba61691875d346cf004f4946fee3/test/db/operators.c.

Also, the details mentioned under heading “3.3.2 JDBSelector” in document "https://wr.informatik.uni-hamburg.de/_media/research:theses:benjamin_warnke_integrating_self_describing_data_formats_into_file_systems.pdf" does not support abovementioned query.

Possible fix: function JDBSelector::j_db_selector_add_selector should take operator information as input and the backend function should use it to append two selectors (https://github.com/julea-io/julea/blob/master/backend/db/sql-generic.c#L1533 - 1547) instead of using the one attached to the first (or preceding) one.

A branch (#105) is added that contains a test case which has the above table and related code.