Re: Next number processing

[rune@xxxxxxx]

Hi Patrick.

Why not use the MAX function of SQL to read the highest event ID directly 
from the event-file.

something like this:

INSERT INTO SCHEMA.EVENTS (ID, ....) VALUES(SELECT MAX(ID)+1 FROM 
SCHEMA.EVENTS, ....)

HTH 

Rune




patrick.odowd@xxxxxxxxxxxxxxxxxxxxxx
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09.03.2004 12:33
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        Subject:        Next number processing


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Hi, 
I have an Event file that has a field called ID as a primary key. ID is an
integer, incremented by 1 for each record added.

I am wondering what the options are for retrieving the next sequence 
number for
the event records. 

At the moment I have a separate file that stores the last event ID used, 
when a
new event record needs to be added I call a static method on a database 
helper
class that returns the next number, code below.

There will only be 1 thread incrementing this event. The volume of events 
is
low, a few per day. It is a batch process.

What I have works but I am wondering if there a better way to do this?

Thanks in advance,
Pat

  public static synchronized int getNextNumber(Connection dbConn,
                                               String collection, String 
key)
throws
      JS_Exception {
    Statement nextNumStm;
    ResultSet nextNumSet;
    String nextNumQry;
    int nextNum = -1;

    try {
      nextNumStm = dbConn.createStatement();
      nextNumStm.executeUpdate("UPDATE " + collection + ".MQ_PARM " +
                               "SET INTVALUE = INTVALUE + 1 WHERE ID =" +
                               '\'' + key + '\'');
      nextNumQry = "SELECT * FROM " + collection + ".MQ_PARM WHERE ID =" +
                   '\'' + key + '\'';
      nextNumSet = nextNumStm.executeQuery(nextNumQry);

      if (nextNumSet.next()) {
        nextNum = nextNumSet.getInt("INTVALUE");
      }
    }
    catch (SQLException e) {
      JS_Utils.processException(e);
      throw new JS_Exception();
    }

    return nextNum;
  }


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