Confusions in hibernate mappings

Hi i am new to hibernate technology and i have few issues.

Suppose if there are two tables. For Example:

Table1 
    table1_ID
    table1_value

Table2
    table2_ID 
    table2_name

If table1_ID is primary key of table1 and (table2_ID and table2_name ) - primary key of table2.

table2_ID of Table2 is referencing table1_ID of Table1 (in hibernate one - to - many mapping)

I have sequence generator for table1_ID. If I try to insert I will give values only for table1_value and table2_name. So now will the sequence created for table1_ID will be assigned to table2_ID ? Because I am getting error stating "null cannot be inserted in table2.ID". How to solve this issue?

Then for dele开发者_StackOverflow社区ting... If I delete gethibernatetype().delete(objectofTable1).... Its again throwing me error

 SQL Error: 2292, SQLState: 23000 
[ERROR] 2010-02-18 19:58:37 (JDBCExceptionReporter.java:logExceptions:78) 
 ORA-02292: integrity constraint  violated - child record found

[ERROR] 2010-02-18 19:58:37 (AbstractFlushingEventListener.java:performExecutions:301) 
 Could not synchronize database state with session 
org.hibernate.exception.ConstraintViolationException: could not delete:

I have set ondelete=cascade too. How to solve this?

In your mappings you have a collection. You have to set it to be cascade=all (or if using annotations - cascade=CascadeType.ALL