in the below ERD. why I am getting errors.

Please check the bold comments and the ERD attached.

Thank you in advance for your help

1. List boats that need engine repair. List boat owner name. Sort by boat id

Ans. 

SELECT BoatId, firstname || ',' || lastname "OwnerName"

FROM Boats

JOIN clients USING (clientID)

JOIN repairorders USING (repairorder#)

WHERE description = 'Engine repair'

ORDER BY Boatid;

-- it says "description invalid identifier"

2. Identify boats and their owners. Owner and boats should be in mixed case. Order by boated.

 

Ans. 

SELECT boatid, INITCAP (firstname) ||','||INITCAP (lastname) "Boat owner"

FROM repairorders,clients

WHERE clients.clientid = boatid

ORDER BY boatid

" No data found. I know that I have data"

3. Provide a list of employees. Include employee id, name, address, and phone number. Names should be in mixed case and phone numbers formatted with hyphens. Sort by employee id.

 

Ans 

SELECT employeeid "Employee ID", INITCAP (empFName)||','|| INITCAP (empLName) " Employee Name ", EmpAddress, SUBSTR(EmpPhone,1,3) ||'-'|| SUBSTR(EmpPhone,4,3)||'-'||SUBSTR(EmpPhone,7,4)||','|| "PHONE"

FROM employees

ORDER BY employeeId;

4. List repair order that includes Navigation, Electrical repair. Include boatid, repairorder#, and repaircode. Sort by repairorder# and repaircode.
 

Ans. 

SELECT BoatId, RepairorderId, Repaircode

FROM RepairOrders

WHERE description IN ('Navigation', 'Electrical repair')

ORDER BY Repairorderid, RepairCode;

5. Provide a list of all repair orders. Include RepairOrderDate, RepairBeginDate, RepairEndDate. Dates should be in MM/DD/YYYY format. If an order is still open specify *** Currently*** in the repairenddate filed.

Ans. 

SELECT RepairOrder#, TO_CHAR(RepairOrderDate,'MM/DD/YYYY')"Repair Order date",TO_CHAR(RepairBeginDate,'MM/DD,YYYY')"Repair begin", NVL2(TO_CHAR(RepairEndDate,'MM/DD/YYYY'),***CURRENTLY***) "Repair ended"

FROM RepairOrders

ORDER BY RepairOrder#;

6. Identify orders totaling over $500. Include boatID.

Ans. 

SELECT DISTINCT BoatId

FROM Repairorders

WHERE( Cost) > 500;

7. What is the price for each service and what is the average price for all services?
 

Ans. 

SELECT RepairCode, Description, cost

(SELECT AVG(cost) AS averageprice

FROM RepairTypes;)

*****Description in repairtypes lists the services offered.****

  

RepairCode (FK) ClientID (FK) ClientID FirstName LastName Address City State ZIP Email Phone RepairOrder# (FK) ClientID (FK) RepairCode ClientID Cost Description Discount PaymentID Payment Method PaidAmount RepairOrder# (FK) RepairOrder# BoatID RepairOrderDate RepairBeginDate RepairEndDate RepairCode (FK) EmployeelD (FK) EmployeelD EmpFName EmpLName Position Salary HireDate EmpAddress EmpCity EmpState ZIPCode EmpEmail EmpPhone