RE: Java code help...

On 11/16/2001 at 11:30:14 AM, java400-l-admin@midrange.com wrote:
Sorry, but I do not agree with you,
your solution is not portable. If the DB is created on another RDB the
columns position may change and the "encapsulated" object will return the
wrong data...
--- end of excerpt ---

Everything is always a compromise, and you
can always do anything more than one way.

Good design represents both portability and performance.
That said, I think this solution is both portable and
higher performing.

I think the main points of Rich's posts are:
1) You pay extra expense from using column names in the
   ResultSet, that you can portably eliminate using
   encapsulation.
2) You should encapsulate your application from the format of your
   DATA. This usually means encapsulating it from the column positions
   (AS WELL AS) the column names, the tables, the schemas, and the
   JDBC objects used to access them.
   Using an appropriate level of abstraction prevents app changes
   due to data model from effecting your application.
3) #1 and #2 can also help in the fact that if you "select *"
   and don't use EVERY single column, you are then wasting
   storage, CPU cycles, and Java object.

This doesn't mean you can't rely on the names in
some places and still get the benefits of the
name == portability idea.

I believe this was Rich's point also.


class DataGetter {
 public static int COL_FLOG  = 1;
 public static int COL_A     = 2;
 public static int COL_DEAD  = 3;
 public static int COL_HORSE = 4;

 ResultSet rs;

 public String getData() {
      ...
      // Note, construct the query so that regardless of
      // table layout/format/DB, we get the columns back
      // in an architected/portable order (i.e. PUBLIC
      // interfaces (including the column numbers above don't change)
      rs = executeQuery("SELECT FLOG, A, DEAD, HORSE FROM BLAH");
 }

 .. Other methods left out ...

 public getFlog() {
    return rs.getString(COL_FLOG);
 }
 public getA() {
    return rs.getString(COL_A);
 }
 public getDead() {
    return rs.getString(COL_DEAD);
 }
 public getHorse() {
    return rs.getString(COL_HORSE);
 }
}





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Fred A. Kulack  -  AS/400e  Java and Java DB2 access, Jdbc, JTA, etc...
IBM in Rochester, MN  (Phone: 507.253.5982   T/L 553-5982)
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