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Tuesday 13 July 2010

Getting the current date in your model layer

Besides the standard way of getting the current date as a String, one could come across the need of inserting in a database table column of date datatype. Thus, the well known code snippet won't be suitable:

 DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
 
 java.util.Date date = new java.util.Date();
 
 String datetime = dateFormat.format(date);
 
 System.out.println("Current Date Time : " + datetime);
 
In case you use ADF business components for your Model project, you get the 
current date in a slightly different way. Consider for example the following code snippet,
from an adf business components, employees entity object: 
 
import oracle.jbo.domain.Date;
...

              
protected void doDML(int operation, TransactionEvent e) {
                if (operation == DML_UPDATE) {
    ...
               histStartDate = row.getEndDate();
              /*Check whether end date equals current date*/
              if (histStartDate.equals(new Date(Date.getCurrentDate()))){
                  System.out.println("End date equals current date!");
                  }
      
In case you need to convert  oracle.jbo.domain.Date to java.util.Date, please consult this:

http://forums.oracle.com/forums/thread.jspa?threadID=2185902&tstart=15

or

http://www.ecotronics.ch/webdesign/javadate.htm
  

Finally, in case you prefer EJB's for your Model project instead, you might consider the following example:

/*Typical current date for DB inserts */
java.util.Date today = new java.util.Date();
java.sql.Date bidDate = new java.sql.Date(today.getTime());
/* public void setBidDate(Date bidDate)*/
newBid.setBidDate(bidDate);

Which is in a sense, the most paradox way of all, since in order to get the current date, you actually need to call getTime()!

References

More help about: using timestamps
http://download.oracle.com/javase/1.4.2/docs/api/java/text/SimpleDateFormat.html

Comments on Oracle XSQL, by M.Thomas

On the bright side, the text is well written, in American English, with a few spelling errors. It provides an introduction to PL/SQL, database design, Oracle Text for Oracle 9i, XML, including XSL, XPath and xsql, which is now considered obsolete(?). Its source code works and could be reused. On the dark side, the book is not an introductory level one, the chapters from the beginning to 14 are more reference like, until the true tutorial building of the web application begins. A javascript or java, introduction is missing, and the paragraphs about XPath are difficult to understand.
All in all, the book can be well used as a reference, provided that several corrections need to be made by the reader, in both its source code and text.