text: -- references rule   
  
  create table t1 (i1 integer primary key);
  
  create table t2 (i2 integer foreign key references t1(i1) on delete set null); 
  drop table t2;
  
  
  create table t2 (i2 integer foreign key references t1(i1) on delete set null on delete set null); 
  drop table t2;
  
  create table t2 (i2 integer foreign key references t1(i1) on update set null );
  drop table t2;
  
  
  create table t2 (i2 integer foreign key references t1(i1) on update set null on update set null);
  drop table t2;
  
  drop table t1;
  
  
  -- create table ordering of attributes    
  -- 
  create table t1 ( i1 integer , i2 integer first);
  drop table t1;
  
  create table t1 ( i1 integer ,  i2 integer , i3 integer after i1);
  drop table t1;
  