text: --+ holdcas on;
  ---- ALTER TABLE ...  CHANGE COLUMN  
  -- constraints : testing add/drop : NOT NULL, 
  -- name : same of different
  -- type : CLOB, BLOB , not type change 
   
  -- 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'; 
  
  
  -- no NULL values
  create table t1 (i int unique, b1 blob, c1 clob);
  insert into t1 values (1,bit_to_blob(X'1aaabbbccc'),char_to_clob('1aaabbbccc'));
  insert into t1 values (2,bit_to_blob(X'2aa3bbbccc'),char_to_clob('2aa3bbbccc'));
  
  --select i, blob_to_bit(b1), clob_to_char(c1) from t1 order by 1;
  
  desc t1;
  
  
  alter table t1 change b1 b1 blob not null;
  
  alter table t1 change c1 c1 clob not null;
  
  -- select i, blob_to_bit(b1), clob_to_char(c1) from t1 order by 1;
  
  desc t1;
  
  drop table t1;
  
  
  
  -- with NULL values
  create table t1 (i int unique, b1 blob, c1 clob);
  insert into t1 values (1,bit_to_blob(X'1aaabbbccc'),char_to_clob('1aaabbbccc'));
  insert into t1 values (2,bit_to_blob(X'2aa3bbbccc'),char_to_clob('2aa3bbbccc'));
  insert into t1 values (2,NULL, NULL);
  
  --select i, blob_to_bit(b1), clob_to_char(c1) from t1 order by 1;
  
  desc t1;
  
  
  alter table t1 change b1 b1 blob not null;
  
  alter table t1 change c1 c1 clob not null;
  
  --select i, blob_to_bit(b1), clob_to_char(c1) from t1 order by 1;
  
  desc t1;
  
  drop table t1;
  
  
  
  
  
  -- 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'; 
  
  
  -- no NULL values
  create table t1 (i int unique, b1 blob, c1 clob);
  insert into t1 values (1,bit_to_blob(X'1aaabbbccc'),char_to_clob('1aaabbbccc'));
  insert into t1 values (2,bit_to_blob(X'2aa3bbbccc'),char_to_clob('2aa3bbbccc'));
  
  --select i, blob_to_bit(b1), clob_to_char(c1) from t1 order by 1;
  
  desc t1;
  
  
  alter table t1 change b1 b1 blob not null;
  
  alter table t1 change c1 c1 clob not null;
  
  --select i, blob_to_bit(b1), clob_to_char(c1) from t1 order by 1;
  
  desc t1;
  
  drop table t1;
  
  
  
  -- with NULL values
  create table t1 (i int unique, b1 blob, c1 clob);
  insert into t1 values (1,bit_to_blob(X'1aaabbbccc'),char_to_clob('1aaabbbccc'));
  insert into t1 values (2,bit_to_blob(X'2aa3bbbccc'),char_to_clob('2aa3bbbccc'));
  insert into t1 values (2,NULL, NULL);
  
  --select i, blob_to_bit(b1), clob_to_char(c1) from t1 order by 1;
  
  desc t1;
  
  
  alter table t1 change b1 b1 blob not null;
  
  alter table t1 change c1 c1 clob not null;
  
  --select i, blob_to_bit(b1), clob_to_char(c1) from t1 order by 1;
  
  desc 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';
  