text: --+ holdcas on;
  ---- ALTER TABLE ...  CHANGE COLUMN  , type change
  -- constraints : no constraints
  -- ordering : no order defined
  -- type change : to char
  -- permissive conversion
  
  set system parameters 'alter_table_change_type_strict=no';
  set system parameters 'error_log_level=warning';
  set system parameters 'error_log_warning=yes';
  
  -------------- varchar 1 : prec same
  create table t1 (s1 varchar(10));
  insert into t1 values ('123'),('1234567890'),('abc');
  
  select s1, length(s1) from t1 order by 1;
  show columns in t1;
  
  alter table t1 change s1 s1 char(10);
  select s1, length(s1) from t1 order by 1;
  show columns in t1;
  
  drop table t1;
  
  
  -------------- varchar 2 : prec increase 
  create table t1 (s1 varchar(10));
  insert into t1 values ('123'),('1234567890'),('abc');
  
  select s1, length(s1) from t1 order by 1;
  show columns in t1;
  
  alter table t1 change s1 s1 char(20);
  
  insert into t1 values('12345678901234567890');
  select s1, length(s1) from t1 order by 1;
  show columns in t1;
  
  drop table t1;
  
  
  -------------- varchar 3 : prec decrease, value in range
  create table t1 (s1 varchar(10));
  insert into t1 values ('123'),('123456789'),('abc');
  
  select s1, length(s1) from t1 order by 1; 
  show columns in t1;
  
  -- should fail
  alter table t1 change s1 s1 char(9);
  select s1, length(s1) from t1 order by 1;
  show columns in t1;
  
  drop table t1;
  
  -------------- varchar 4 : prec decrease, value out of range
  create table t1 (s1 varchar(10));
  insert into t1 values ('123'),('1234567890'),('abc');
  
  select s1, length(s1) from t1 order by 1; 
  show columns in t1;
  
  -- should fail
  alter table t1 change s1 s1 char(9);
  select s1, length(s1) from t1 order by 1;
  show columns in t1;
  
  drop table t1;
  commit;
  --+ holdcas off;
  
  set system parameters 'error_log_level=syntax';
  set system parameters 'error_log_warning=no';
  