Graph Database for Collaborative Communities - Community-Built Databases: Research and Development - page 212

Fig. 9.5 Queries with QGRAPH
Fig. 9.6 GOOD data model schema and instance
GOOD contains five operators. Four of them correspond to elementary manipu-
lation of graphs: addition of nodes and edges, and deletion of nodes and edges. The
fifth operation called 'abstraction' is used to group nodes on the basis of common
functional or nonfunctional properties. The specification of all these operations
relies on the notion of pattern to describe subgraphs in an object-based instance.
GOOD presents other features such as macros (for more succinct expression of
frequent operations), computational-completeness of the query language, and sim-
ulation of object-oriented characteristics such as encapsulation and inheritance.
A simple path can be discovered by using a pattern. Moreover, GOOD is
incapable of finding a path with no fixed length. Figure 9.7 illustrates two examples
of GOOD query: the first query is to find students and their supervisors; the second
one is to find students working on the ontology topic. This language was followed
by the proposals GMOD [ 5 ], PaMaL [ 7 ], and GOAL [ 16 ]. These languages use
GOOD's principal features and add several new functionalities.
9.2.2.2 SQL-Like Languages
SQL-like languages are declarative rule query languages that extend traditional
SQL and propose new SQL-like operators for querying graphs and objects [ 17 - 19 ].