class departments at undefined( ) {
"department_id : integer"
"department_name : varchar(30)"
"manager_id : integer"
"location_id : integer"
};

class locations at undefined( ) {
"location_id : integer"
"street_address : varchar(40)"
"postal_code : varchar(12)"
"city : varchar(30)"
"state_province : varchar(25)"
"country_id : varchar(2)"
};

class countries at undefined( ) {
"country_id : varchar(2)"
"country_name : varchar(40)"
"region_id : integer"
};

class regions at undefined( ) {
"region_id : integer"
"region_name : varchar(40)"
};

class employees at undefined( ) {
"employee_id : integer"
"first_name : varchar(20)"
"last_name : varchar(25)"
"email : varchar(25)"
"phone_number : varchar(25)"
"hire_date : date"
"job_id : varchar(10)"
"salary : numeric"
"commission : number"
"manager_id : integer"
"department_id : integer"
};

class job_history at undefined( ) {
"employee_id : integer"
"start_date : date"
"end_date : date"
"job_id : varchar(10)"
"department_id : integer"
};

class jobs at undefined( ) {
"job_id : varchar(10)"
"job_title : varchar(35)"
"min_salary : numeric"
"max_salary : numerc"
};

dependency a1 from departments to locations at undefined( ) undefined( );
dependency a2 from locations to countries at undefined( ) undefined( );
dependency a3 from countries to regions at undefined( ) undefined( );

dependency a4 from departments to employees at undefined( ) undefined( );

dependency a5 from employees to departments at undefined( ) undefined( );
dependency a6 from employees to jobs at undefined( ) undefined( );

dependency a7 from job_history to jobs at undefined( ) undefined( );
dependency a8 from job_history to departments at undefined( ) undefined( );
dependency a9 from job_history to employees at undefined( ) undefined( );