text: --+ holdcas on;
  ---- ALTER TABLE ...  CHANGE COLUMN  , type change
  -- constraints : not NULL
  -- ordering : no order defined
  -- name : same name
  -- type : DATE
  
  
  -- adding 'not null'  : strict mode
  set system parameters 'alter_table_change_type_strict=yes';
  set system parameters 'error_log_level=warning';
  set system parameters 'error_log_warning=yes'; 
  
  -------------- DATE 1 : not change
  create table t1 (d date);
  insert into t1 values (date'03/04/1999');
  insert into t1 values (date'11/12/2001');
  insert into t1 values (null);
  
  select * from t1 order by 1;
  show columns in t1;
  
  alter table t1 change d d date not null;
  -- should be ok:
  insert into t1 values (date'12/11/1996');
  -- should fail
  insert into t1 values (null);
  select * from t1 order by 1;
  show columns in t1;
  
  drop table t1;
  
  
  
  -- adding 'not null'  : permissive  mode
  set system parameters 'alter_table_change_type_strict=no';
  set system parameters 'error_log_level=warning';
  set system parameters 'error_log_warning=yes'; 
  
  
  -------------- DATE 1 : not change
  create table t1 (d date);
  insert into t1 values (date'03/04/1999');
  insert into t1 values (date'11/12/2001');
  insert into t1 values (null);
  
  select * from t1 order by 1;
  show columns in t1;
  
  alter table t1 change d d date not null;
  -- should be ok:
  insert into t1 values (date'12/11/1996');
  -- should fail
  insert into t1 values (null);
  select * from t1 order by 1;
  show columns in t1;
  
  drop table t1;
  
  set system parameters 'alter_table_change_type_strict=no';
  commit;
  --+ holdcas off;
  
  set system parameters 'error_log_level=syntax';
  set system parameters 'error_log_warning=no'; 
  