text: DROP TABLE basecell;
  DROP TABLE basedef;
  DROP TABLE base;
  DROP TABLE stationary;
  
  CREATE TABLE basecell (
          person     NUMBER(10),     -- uid of person
  	baseid     NUMBER(10),     -- uid of the base
  	nw         VARCHAR2(40),   -- network
  	lac        NUMBER(10),     -- local area code
  	cellid     NUMBER(10)      -- cell identifier
  );
  
  CREATE TABLE basedef (
  	person     NUMBER(10),     -- uid of person
  	baseid     NUMBER(10),     -- uid of the base
  	name       VARCHAR2(50),
  	time_spent NUMBER(10),     -- seconds spent in this base
  	num_visits NUMBER(10)      -- number of visits to the base
  );
  
  CREATE TABLE base (
  	person     NUMBER(10),
  	base       NUMBER(10),
  	prev_base  NUMBER(10),
  	next_base  NUMBER(10),
  	valid_from  DATE,
  	valid_until DATE,
  	duration   NUMBER(10),
  	seqno      NUMBER(10)
  );
  
  CREATE TABLE stationary (
  	person     NUMBER(10),
  	valid_from  DATE,
  	valid_until DATE,
  	duration   NUMBER(10),
  	seqno      NUMBER(10)
  );
  
  