text: --+ holdcas on;
  ---- ALTER TABLE ...  CHANGE COLUMN  
  -- constraints : testing add/drop : NOT NULL, 
  -- ordering : no order defined
  -- name : same of different
  -- type : numeric , not type change 
  -- other :
  
  
  -- adding 'not null'  : strict mode
  set system parameters 'alter_table_change_type_strict=yes';
  
  
  create table t1 ( n numeric(16,8) );
  insert into t1 values (12.123123),(0),(NULL),(99999999.99999999),(-99999999.99999999);
  select * from t1 order by 1;
  show columns in t1;
  
  alter table t1 change n n1 numeric(16,8) not NULL;
  
  select * from t1 order by 1;
  show columns in t1;
  
  -- should fail:
  insert into t1 values (NULL);
  
  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'; 
  
  create table t1 ( n numeric(16,8) );
  insert into t1 values (12.123123),(0),(NULL),(99999999.99999999),(-99999999.99999999);
  select * from t1 order by 1;
  show columns in t1;
  
  alter table t1 change n n1 numeric(16,8) not NULL;
  
  select * from t1 order by 1;
  show columns in t1;
  
  -- should fail:
  insert into t1 values (NULL);
  
  drop table t1;
  
  
  
  -- adding 'not null'  : permissive mode , but no existing NULL -> no warning
  set system parameters 'alter_table_change_type_strict=no';
  set system parameters 'error_log_level=warning';
  set system parameters 'error_log_warning=yes'; 
  
  create table t1 ( n numeric(16,8) );
  insert into t1 values (12.123123),(99999999.99999999),(-99999999.99999999);
  select * from t1 order by 1;
  show columns in t1;
  
  alter table t1 change n n1 numeric(16,8) not NULL;
  
  select * from t1 order by 1;
  show columns in t1;
  
  -- should fail:
  insert into t1 values (NULL);
  
  drop table t1;
  
  set system parameters 'alter_table_change_type_strict=no';
  
  commit;
  --+ holdcas off;
  