The graph provides a powerful methodology to solve a lot of real-world problems. There has been much research on graph representations and algorithms. But, there are still many difficulties to apply graphs to practical domains.
This paper proposes a graph library developed on the relational database. Graphs are represented in the form of relational tables and then saved in a database. Graph operations are coded in terms of database languages such as the SQL. Users of the graph library can efficiently manage a large amount of graph data. Furthermore, graphs saved in the database can be concurrently shared among many users. The proposed graph library will be useful to represent and solve real world problems efficiently.