2.1.18b. Outer joins

  • Outer joins are crucial in the real-world
  • Databases often contain NULLs (3VL)
  • Analysis of where the crucial data is across a relationship
  • Previous example, only get project data for managed projects
    • SELECT project.*, employee.*
    • FROM project INNER JOIN employee
    • ON project.mgrssn = employee.ssn;

Inner join example