Significnce of making the Connection object explicitly as null

Question

Iam using java.sql.Connection object to make connection to DB400 database and in the finally block closing the connection as con.close();
90% of the time query is executing fine and getting correct results. But some times the updated values in the data base are not getting reflected in the result set. ie: ResultSet object is not refreshing properly(not always but sometimes). After making the code in the finally block as follows I feel it is working fine
if(con != null)
con.close();
con=null;
Can some one explain the significance of making an object explicitly to null.

Answer 1

I am facing the same issue again. The resultSet and the stament are getting closed properly but the query is not fetching the updated results. If i execute the same query using a client(WinSQL), then the updated values are reflected. Also if i change any of the where conditions in the query(adding one more 'and' condition or 'or' condition ), then the query is giving correct results. Is there any resultSet caching occurs in websphere