Why would you want a Left Outer Join as shown below?

Primary Physician 9 [Primary Physician 101 [Doctor First Name] [Doctor Last Name] Specialty [Years of Experience! Hospital Visit 8 [Visit ID) [Patient ID [Primary Physician ID [Discharge Details TD] [Admit Typel [Date of Arrival [Date of Admission) Visit Type Patient Last Name [Primary Location) Discharge Details 8 Discharge ID) [Discharge Date] [Discharge Location] [Discharge instructions) Patient 7 [Patient ID [Patient First Name] [Patient Last Name] [Patient Birth Date! [Patient City [Patient State) [Patient Zip Code] [Patient County) [Patient Marital Status] [Patient Gender Hospital Visit Discharge Details 0 Patient Primary Physician Primary Physician 9 [Primary Physician 101 [Doctor First Name] [Doctor Last Name] Specialty [Years of Experience! Hospital Visit 8 [Visit ID) [Patient ID [Primary Physician ID [Discharge Details TD] [Admit Typel [Date of Arrival [Date of Admission) Visit Type Patient Last Name [Primary Location) Discharge Details 8 Discharge ID) [Discharge Date] [Discharge Location] [Discharge instructions) Patient 7 [Patient ID [Patient First Name] [Patient Last Name] [Patient Birth Date! [Patient City [Patient State) [Patient Zip Code] [Patient County) [Patient Marital Status] [Patient Gender Hospital Visit Discharge Details 0 Patient Primary Physician