LEFT OUTER JOIN Example in SQL SERVER 2005

This join returns all the rows from the left table with the matching rows from the right table. If there are no columns matching in the right table, it returns NULL values.

Use this when you only want to return rows that have matching data in the left table, even if there's no matching rows in the right table.
     Ex:

     Left Table(emp Table)

         ------------------------------------------------------------------------
         empID    FirstName    LastName    UserName
         ------------------------------------------------------------------------
              1             John         Miller             John
              2             Steve        Jobs              Steve
              3          Billgates      john              Billgates
              4             Ozzy         Ozzbourne    Ozzy
              5            Homer        Gain             Homer
        --------------------------------------------------------------------------

     Right Table(dept Table)

         ------------------------------------------------------
            empID        DeptName
         ------------------------------------------------------
               1                  IT
               2          Networking
               3          Networking
               4          Networking
              12          Admin
         ------------------------------------------------------
    
     Query:

     SELECT * FROM emp AS e
     LEFT JOIN dept AS d
     ON e.empid = d.empid

    result:

    empID     FirstName    LastName        UserName    IndividualId    AccessLevel
        1             John             Miller                 John                 1                     IT
        2             Steve           Jobs                    Steve                2             Networking
        3             Billgates      john                    Billgates          3             Networking
        4             Ozzy           Ozzbourne          Ozzy                4             Networking
        5             Homer        Gain                    Homer        NULL          NULL