sql: Customer and branch query in company database

samedi 25 avril 2015

I have following four tables in my database :

EMPLOYEE

PK: employeeID;     
FK: empBranch references BRANCH;
FK: empSupervisor references EMPLOYEE

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BRANCH

PK: branchNumber
FK: branchManager references EMPLOYEE

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CUSTOMER

PK: customerID

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ORDERS

PK: orderNumber
FK: customerID references CUSTOMER; 
FK: salesPerson references EMPLOYEE

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Now I need to list out these two things :

The Employee_ID and name of salespersons who have sold only to customers located in the same city as the city in which the salesperson’s branch is located.
The Employee_ID and name of salespersons who have sold to every customer located in the same city as the city in which the salesperson’s branch is located.

Please help me to answer both queries

sql