st.dispose();
st = connection.prepare("drop table if exists com_subgraph_edge;",false);
st.stepThrough();
st.dispose();
st = connection.prepare("drop table if exists com_subgraph_vertex;",false);
st.stepThrough();
st.dispose();
st = connection.prepare("drop table if exists com_edge_attribute;",false);
st.stepThrough();
st.dispose();
st = connection.prepare("drop table if exists com_vertex_attribute;",false);