How to get option value from database?

Friends i have database by name employee-application. It has 3 tables as follows

create table departments
(
 department_id int(20) not null AUTO_INCREMENT PRIMARY KEY,
 department_name varchar(30)  not null
);

Then,

create table designation
(
 designation_id int(20) not null AUTO_INCREMENT PRIMARY KEY,
 designation_name varchar(30) not null
);

Finally,

create table employee
(
 employee_id int(20) AUTO_INCREMENT NOT NULL,
 employee_name varchar(30) not null,
 department_name varchar(30),
 designation_name varchar(30),
 salary int(20) not null,
 FOREIGN KEY(department_name) references departments(department_id),
 FOREIGN KEY(designation_name) references designations(designation_id)
 );

Now i want to create form for adding new employee to the table. Here is my doubt, how do i get department_name and designation_name to my form as option/dropdown value from database??? Can someone help me to find a path to solve this..!!!