How to use Oracle Sequence for auto increment column

While reading through this thread http://forum.sun.com/jive/thread.jspa?threadID=99306 I had to check out how to invoke sequence.nextval for new row being appended.

Here's how i did achieve this: 

1. Created a Sequence and a Table: 
CREATE SEQUENCE userid_seq MINVALUE 1 START WITH 1 INCREMENT BY 1 NOCACHE; 
create table user_seq_test ( seq_col int not null primary key, char_col char(10) ); 

2. Creating a Page to append rows into this table: 
Add a datadource (say ora9i) to access this database table in Servers Window. Create a New Project, drag and drop user_seq_test table onto page. Dropa text field and bind it to user_seq_test.char_col. Add a button for "Append Row". Add a message group to be able to see the error messages on the page, when it happens.

In the prerender, append a row to the dataprovider and get the sequence value for the new row and set it:

    
    
    
    

     
     
     
     
     try
     
     
     
      {
     RowKey rk 
     
     
     
     =
     
     
     
      user_seq_testDataProvider.appendRow();
     user_seq_testDataProvider.setCursorRow(rk);
             
     Connection conn 
     
     
     
     =
     
     
     
      
     
     
     
     null
     
     
     
      ;
     Statement sqlStatement 
     
     
     
     =
     
     
     
      
     
     
     
     null
     
     
     
      ;
     ResultSet rs 
     
     
     
     =
     
     
     
      
     
     
     
     null
     
     
     
      ;
             
     javax.naming.Context ctx 
     
     
     
     =
     
     
     
      
     
     
     
     new
     
     
     
      javax.naming.InitialContext() ;
     DataSource ds 
     
     
     
     =
     
     
     
      (DataSource)ctx.lookup(
     
     
     
     "
     
     
     
     java:comp/env/jdbc/ora9i
     
     
     
     "
     
     
     
     ) ;                      
     conn 
     
     
     
     =
     
     
     
      ds.getConnection() ;                        
     
     
     
     
     //
     
     
     
      setup the connection             
     
     
     
     
 
     
     
     
         conn.setAutoCommit(
     
     
     
     true
     
     
     
     ) ;                         
     
     
     
     
     //
     
     
     
      execute the query            
     
     
     
     
 
     
     
     
         sqlStatement 
     
     
     
     =
     
     
     
      conn.createStatement() ;
     rs 
     
     
     
     =
     
     
     
      sqlStatement.executeQuery(
     
     
     
     "
     
     
     
     select userid_seq.NEXTVAL from dual
     
     
     
     "
     
     
     
      ) ;
     rs.next() ;
     
     
     
     
     int
     
     
     
      nextvalue 
     
     
     
     =
     
     
     
      rs.getInt(
     
     
     
     1
     
     
     
     ) ;
     user_seq_testDataProvider.setValue(
     
     
     
     "
     
     
     
     seq_col
     
     
     
     "
     
     
     
     , 
     
     
     
     new
     
     
     
      Integer(nextvalue));
     rs.close();
     sqlStatement.close();
     conn.close();
 } 
     
     
     
     catch
     
     
     
      (Exception ex) {
     error(ex.getMessage());
     log(
     
     
     
     "
     
     
     
     Error Description
     
     
     
     "
     
     
     
     , ex);
 }
    
    
    
    

In the append Row Button action:

    
    
    
    

     
     
     
     
     try
     
     
     
      {
             user_seq_testDataProvider.commitChanges();
             user_seq_testDataProvider.refresh();
  } 
     
     
     
     catch
     
     
     
      (Exception ex) {
             log(
     
     
     
     "
     
     
     
     Error Description
     
     
     
     "
     
     
     
     , ex);
             error(ex.getMessage());
  }
    
    
    
    

So, when we want to use Sequence.NEXTVAL, you need to fetch the value and set this value on the auto-increment column in the appended row.

We could use similar technique for calling functions and stored procedures.

Author:  Sakthi

Link  :  http://blogs.sun.com/sakthi/entry/a_scenario_with_oracle_sequence