1. INNER JOIN
   1. SELECT * FROM employee INNER JOIN department ON employee.DepartmentID = department.DepartmentID
   2. SELECT * FROM employee, department WHERE employee.DepartmentID = department.DepartmentID
   3. Topic
2. OUTER JOIN
   1. left outer join
      1. SELECT distinct * FROM employee LEFT OUTER JOIN department ON employee.DepartmentID = department.DepartmentID
      2. SELECT * FROM employee, department WHERE employee.DepartmentID = department.DepartmentID(+)
      3. Topic
   2. right outer join
      1. SELECT * FROM employee RIGHT OUTER JOIN department ON employee.DepartmentID = department.DepartmentID
      2. SELECT * FROM employee, department WHERE employee.DepartmentID(+) = department.DepartmentID
      3. Topic
   3. full outer join
      1. SELECT * FROM employee FULL OUTER JOIN department ON employee.DepartmentID = department.DepartmentID
      2. Topic
3. CROSS JOIN
   1. SELECT * FROM employee CROSS JOIN department;
   2. SELECT * FROM employee, department;
   3. Topic
4. Bảng dữ liệu