%META:TOPICPARENT{name="VirtTipsAndTricksGuide"}%

---+How can I delete graphs using stored procedure?


The following script demonstrates the use of custom stored procedures for deleting graph(s). It first creates a table <code><nowiki>GRAPHS_TO_DELETE</nowiki></code>, into which the names of the graphs to be deleted should be inserted, as follows:

<verbatim>
use MYUSR;

create procedure GRAPHS_TO_DELETE_SP (in gd_iris any)
{
  declare gd_iri iri_id;
  declare dp, row any;
  result_names (gd_iri);
  dp := dpipe (0, '__I2IDN');
  foreach (varchar iri in GD_IRIS) do
    {
      dpipe_input (dp, iri);
    }
  while (0 <> (row := dpipe_next (dp, 0)))
    {
      result (row[0]);
    }
}
;

drop view GRAPHS_TO_DELETE_VIEW;
create procedure view GRAPHS_TO_DELETE_VIEW as MYUSR.DBA.GRAPHS_TO_DELETE_SP (gd_iris) (gd_iri any);

create procedure DELETE_GRAPHS (in g_iris any)
{
  declare g_iids any;
  if (not isvector (g_iris) and g_iris is not null)
    signal ('22023', '.....', 'The input argument must be an array of strings or null');
  if (not length (g_iris))
    return 0;
  delete from DB.DBA.RDF_QUAD where G in (select * from GRAPHS_TO_DELETE_VIEW where gd_iris = g_iris) option (loop exists);
  return row_count ();
}
;
</verbatim>

Finally call the procedure <code>DELETE_GRAPHS</code> to perform the deletion of the specified graphs. Note it does not return a result set and can be called as follows:

<verbatim>
SQL> select MYUSR.DBA.DELETE_GRAPHS (vector ('g1', 'g2', 'g3'));
</verbatim>

This will return the number of triples removed from the specified graphs. 


<b>Note</b>: the procedure only applies to the cluster so to get IRI IDs via partitioned pipe (DAQ). It is not usable on single.


---+++Related
   
   * [[VirtTipsAndTricksGuide][Virtuoso Tips and Tricks Collection]]
   * [[http://docs.openlinksw.com/virtuoso/sparqlextensions.html#rdfsparulexamples14][How can I delete triples from a graph?]]