text: drop table if exists track, album;
  CREATE TABLE album( id_1 char(10) , CONSTRAINT "pk_album_id" PRIMARY KEY (id_1));
  CREATE TABLE track( album_1 char(10) , FOREIGN KEY (album_1) REFERENCES album(id_1));
  select * from _db_attribute where class_of.class_name = 'album' order by 1;
  select * from db_attribute where class_name = 'album' order by 1;
  drop table if exists track, album;
  
  drop table if exists foo;
  create table foo( id int primary key, d double, vc varchar(128) );
  alter table foo rename attribute vc as vch, rename attribute d as d2;
  select * from db_attribute where class_name = 'foo' order by attr_name;
  drop table if exists foo;
  
  drop table if exists doo;
  create table doo (a int);
  alter table doo add attribute b int;
  select * from db_attribute where class_name = 'doo' order by 1;
  drop doo;
  
  drop table if exists father,child;
  create table father (a int);
  create table child (b int) ;
  alter table child add superclass father;
  alter table father add attribute c int;
  select * from db_attribute where class_name = 'child' order by 1;
  drop father,child;
  
  drop table if exists father_fk,father_pk,child;
  create table father_pk (a int primary key,b varchar(10));
  create table father_fk (b int, c int, FOREIGN KEY (c) REFERENCES father_pk(a)) ;
  create table child(d varchar(20)); 
  alter table child add superclass father_fk;
  alter table father_fk add attribute c int;
  select * from db_attribute where class_name = 'child' order by 1;
  drop table if exists father_fk,father_pk,child;
  
  
  drop table if exists father1,father2,child;
  create table father1 (a1 int);
  create table father2 (a2 int);
  create table child (b int) ;
  alter table child add superclass father1,father2;
  alter table father1 add attribute c int;
  select * from db_attribute where class_name = 'child' order by 1;
  drop table if exists father1,father2,child;
  
  drop table if exists father1,father2,child;
  create table father1 (a int);
  create table father2 (a int);
  create table child (a int) ;
  alter table child add superclass father1,father2 inherit a of father1 as purpose,a of father2 as alias ;
  select * from db_attribute where class_name = 'child' order by 1;
  drop table if exists father1,father2,child;
  
  
  drop table if exists father,child;
  create table father (a int);
  create table child under father ;
  select * from db_attribute where class_name = 'child' order by 1;
  drop father,child;
  
  