title: The correct way to update/query from DB
body: <p>I am abit new with working with DatatBases from Java, and I have been wondering if I am working in a correct way. In my code all the DB interface is done within one class called DataAccess, an example of my code:</p>
  
  <p>Please note that I opened a connection (<code>connBlng</code>) before entering the function  <code>isValidOperator()</code>. </p>
  
  <p>Is this the correct way to work or should I open and close a  connection everytime I need to access the DB?  </p>
  
  <pre><code>if(da.StartBlngConnection() == null)
      return "ERROR"
  DataAccess da = new DataAccess();
  da.isValidOperator("123")       
  
  //this is code from DataAccess Class
  public Boolean isValidOperator(String dn) {
      System.out.println( npgReqID + " - " + LOG_TAG + "inside isValidOperator : " + dn);
      PreparedStatement prepStmt = null;
      ResultSet queryResult = null;
      try{
          prepStmt = connBlng.prepareStatement("select network_id, network_identifier from operators where network_identifier = ?"); 
          prepStmt.setString(1, dn);
          queryResult = prepStmt.executeQuery();
          if (queryResult.next()) {
              return true;
          }
      }catch(Exception e){
          System.out.println(npgReqID + " - "  + e);
          DBLog("", new Date(),"" , npgReqID , "" ,"" , MakeSureNotOutOfRange(GetStackTrace(e),4000), "" , "");
          return false;
      } finally{
          closeStatmentandRS(queryResult, PreparedStatement);
      }
  
      return false;
  } 
  </code></pre>