Return rows from a PL/pgSQL function

Question

I have a procedure in PostgreSQL:

CREATE OR REPLACE FUNCTION get_geom_difference()
RETURNS void AS
$$
BEGIN
SELECT filedata.num,st_area(ST_Difference(ST_TRAN         


        

Answer 1

Although Erwin provided a great answer, I thought I'd share a version in which the function takes params, and I'm using the new postgres return query syntax within the body of the function. The difference is that it seems to set params you have to use the PreparedStatement interface rather than the higher level Statement. here's my pg function

CREATE OR REPLACE FUNCTION gettools(_userid bigint)
  RETURNS table(id bigint,itemname character varying(250)) AS
$BODY$

begin   
    return query 
    select distinct a.id, a.itemname 
    from tool a inner join tooltie b
     on a.id = b.toolid 
     and b.userid=_userid;
end;
$BODY$
  LANGUAGE plpgsql STABLE
  COST 100;

and here's my java that simply fills a map with data

  private static final String GET_DATASOURCES = "select * from getdatasources(?)";

    public Map getAuthDataSources(Long userid) {
        Map auths = new TreeMap<>();
        try {
          if (connection == null || connection.isClosed()) {
            init();
          }
          PreparedStatement cs = connection.prepareStatement(GET_DATASOURCES);
          // this is where to set the param ? for the function
          cs.setLong(1, userid);
          connection.setAutoCommit(false);        
          ResultSet result = cs.executeQuery();

          while (result.next()) {
            Long id = result.getLong(1);
            String itemname = result.getString(2);
            auths.put(id, itemname);
          }
          cs.close();
          connection.commit();
          connection.setAutoCommit(true);
          connection.close();
        } catch (SQLException ex) {
          LOG.error("error getting data sources", ex);

        }
        return auths;
      }

Hope this helps someone.