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How to Update a table based on object values?

Hi,

I have some objects that are from this class:

class Email{
private String emailaddress;
private String TypeCode;
private String SubCode;
private String emailaddressnew;
private Date DateTime;
}

I populated an array of these objects as Email[] array.

These Email[] array will be used to update the following table:


Table: Email
EMAIL_TEXT        Varchar2(100) not null PK
FAILURE_COUNT  Number(4)
IN_DATE             Date
OUT_DATE          Date
SRC                    Varchar2(3)
CREATETMS       Timestamp(6)
UPDATETMS       Timestamp(6)


Based on the  TypeCode value of the object, I will need to update certain fields of the table.

But before this I will have to make sure that the email address even exists in the table.
It is possible that certain email addresses will not be in the table --- in this case I will simply have to do a insert into this table with some object values and appropriate values.

So, if the email address does not exists in the table, do a insert
      if the email address exists in the table, do a update.

Need some help on logic and jdbc illustration on this...


Thanks.
_Esam.
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_Esam
Asked:
_Esam
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4 Solutions
 
CEHJCommented:
What DB is it?
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_EsamAuthor Commented:
It's Oracle 9.2

_Esam
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CEHJCommented:
In order to keep your code flexible, you could do a select first, using an updatable ResultSet, which you could use if it returns a row, or insert otherwise
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_EsamAuthor Commented:
Could you please illustrate as to how?

I can get the updatable resultset and use it to update or to insert otherwise?

WILL THIS BE EFFICIENT IF THERE ARE MILLIONS OF RECORDS?

Thax.
_Esam....
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CEHJCommented:
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_EsamAuthor Commented:
Ok.. I got some idea but not quit :)

I still need to figure out how I set up the logic to see if the record exists in the database table,
If it exists, then do the update
If it does not exist, then do the insert?


Thanks.
_Esam...

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CEHJCommented:
That's the logic yes. The latter you'd do with moveToInsertRow (see article at last link)
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_EsamAuthor Commented:
I am a little confused!

Do I use a Statement?   PreparedStatement ? ResultSet (Updatabae) ?  addBatch for the Statement objects???


Let me know ...

_Esam
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CEHJCommented:
>>PreparedStatement ? ResultSet (Updatabae) ?

the above two. Read the last article
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_EsamAuthor Commented:
Well, I read the last article...
I think I understood what is said there but not how I relate my problem there???

I don't see how I can use PreparedStatement with Updateable ResultSet !!!

It has to be Statement object?

Let me know...

Thax.
_Esam.
0
 
_EsamAuthor Commented:
I wonder if there is an alternate way of doing this ---- avoing updatable resultset ...

Could it be very time consuming if there are millions of records??


_Esam.....
0
 
CEHJCommented:
An alternative would be to do a select followed by an insert, and yet another would be to catch dup key and then update
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_EsamAuthor Commented:
I am trying to formulate the logic...a little stuck with it..

_Esam...
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CEHJCommented:
ResultSet rs = ps.executeQuery();
if (rs.next()) {
    // you can update it
}
else {
    rs.moveToInsertRow();
    // do insert
}
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_EsamAuthor Commented:
Hi CEHJ,

Yes, I finally started thinking like you said above...
I will have to implement and test it tomorrow..done for the day....
I will have to get back to it once more...(sorry to keep the Question hanging.. i don't like that .. :)

Thanks...much..

Regards...
_Esam....
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CEHJCommented:
No problem
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objectsCommented:
> Could it be very time consuming if there are millions of records??

absolutely

if you've got lots of rows then use a batch

http://javaalmanac.com/egs/java.sql/BatchUpdate.html
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_EsamAuthor Commented:
So confused now :)

What do I do?

I want to insert rows if they don't exist in the database table!
I want to update rows if they exist in the database table!

The table will have 4-5 millions of records...

Use sepater queries  for these two functionalities?
Use one query with Updatable ResultSet (insert/update)  - how I use PreparedStatement with this?

Let me know ..
Thanks..
_Esam
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_EsamAuthor Commented:
This is my m_Select :
String m_Select = "SELECT EMAILTEXT, FAILURECT, INDATE, OUTDATE, SRC, CTMS, UTMS FROM EMAIL WHERE EMAILTEXT= ?";
 
public void upDateContent(){

PreparedStatement   lPStatement         = null;
boolean                      lInsertComplete    = false;

mConnection.setAutoCommit(false);

lPStatement  = mConnection.prepareStatement(m_Select, ResultSet.TYPE_SCROLL_SENSITIVE,
                 ResultSet.CONCUR_UPDATABLE);
     //rs = mConnection.createStatement();
     // add the statements for batch processing
     for (int i=0; i<lRecords.length; i++)  //my Email[] - array of Email objects
          
     {
   

               lPStatement.setString(1, lRecords[i].getEmailAddress());
              
               lResult = lPStatement.executeUpdate();
              
               System.out.println("Nuber of records inserted:  " + lResult);
           }
           else{
                 
           }
          
           //lStatement.executeQuery(m_insertEmailRecordSQL);
           //lPStatement = mConnection.prepareStatement(m_Insert);
          
     }
 
     mConnection.commit();
     lInsertComplete = true;

}

How/where do I create the ResultSet?
Such that I can do it like you said above:

ResultSet rs = ps.executeQuery();
if (rs.next()) {
    // you can update it
}
else {
    rs.moveToInsertRow();
    // do insert
}

_Esam
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CEHJCommented:
:-)
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