text: ---- ALTER TABLE ...  CHANGE COLUMN  , type change
  -- constraints : no constraints
  -- ordering : no order defined
  -- name : same name
  -- type : DATE
  
  
  -------------- DATE 1 : to varnchar, prec to small
  create table t1 (d date);
  insert into t1 values (date'2001-03-04');
  insert into t1 values (date'1999-04-06');
  
  select * from t1 order by 1;
  show columns in t1;
  
  alter table t1 change d s1 nchar varying(9);
  
  -- should be ok:
  insert into t1 values (date'2001-11-10');
  
  insert into t1 values ('abc');
  
  select * from t1 order by 1;
  show columns in t1;
  
  drop table t1;
  
  -------------- DATE 2 : to varnchar, prec enough
  create table t1 (d date);
  insert into t1 values (date'2001-03-04');
  insert into t1 values (date'1999-04-06');
  
  select * from t1 order by 1;
  show columns in t1;
  
  alter table t1 change d s1 nchar varying(10);
  
  -- should be ok:
  insert into t1 values (date'2001-11-10');
  
  insert into t1 values ('abc');
  
  select * from t1 order by 1;
  show columns in t1;
  
  drop table t1;
  
  -------------- DATE 3 : to varnchar, prec not specified
  create table t1 (d date);
  insert into t1 values (date'2001-03-04');
  insert into t1 values (date'1999-04-06');
  
  select * from t1 order by 1;
  show columns in t1;
  
  alter table t1 change d s1 nchar varying;
  
  -- should be ok:
  insert into t1 values (date'2001-11-10');
  
  insert into t1 values ('abc');
  
  select * from t1 order by 1;
  show columns in t1;
  
  drop table t1;
  
  