4. 13134, 13134, 38, Clerk
5. B returned deptID 38 clerks because it takes each result separately.  Naughton makes over $13,000, but Abraham makes less than $13,000.  Instead of seeing them as a group, B saw them individually because the WHERE clause doesn't use GROUP BY.  C saw them together because it has a HAVING clause.  The HAVING clause runs the results through as a group and only returns groups in which all the data fulfills the query parameters.
6. C
7. SELECT (UnitPrice * Quantity) AS LineItemSum,
 CASE
    WHEN (GROUPING(EmployeeID) = 1) THEN 9999
    ELSE (EmployeeID)
 END AS EmployeeID,
 CASE
    WHEN (GROUPING(ShipCity) = 1) THEN '*All*'
    ELSE (ShipCity)
 END AS ShipCity
FROM "Order Details" INNER JOIN Orders
ON "Order Details".OrderID = Orders.OrderID
GROUP BY (UnitPrice * Quantity), EmployeeID, ShipCity WITH CUBE
8. SELECT COUNT(OrderID) as 'Count', EmployeeID, Max(Freight) as 'Max Freight'
FROM Orders
Group By EmployeeID
HAVING MAX(Freight) < 600
9. SELECT Max(HireDate) AS LatestHireDate, Min(HireDate) AS EarliestHireDate
FROM Employees
10. SELECT FirstName + ' ' + LEFT(LastName, 1) + '.' AS Contact,
       RIGHT(HomePhone,8) AS Phone
FROM Employees
ORDER BY Contact
11 - 14 brad put in discord i think
15. The join columns are invalid
16. SELECT country, COUNT(*) AS [customer cnt]

FROM Customers

GROUP BY country

HAVING COUNT(*) > 5
17. INSERT INTO Shippers (CompanyName, Phone) VALUES ('ParcelForce', '0800-22446')
18.
SELECT VendorName, AccountDescription, COUNT(*) AS LineItemCount
    , SUM(InvoiceLineItemAmount) AS LineItemSum
FROM Vendors
    JOIN Invoices ON Vendors.VendorID = Invoices.VendorID
    JOIN InvoiceLineItems ON Invoices.InvoiceID = InvoiceLineItems.InvoiceID
    JOIN GLAccounts ON InvoiceLineItems.AccountNo = GLAccounts.AccountNo
GROUP BY VendorName, AccountDescription
ORDER BY VendorName, AccountDescription;
19.
SELECT VendorID, InvoiceDate, InvoiceTotal,
    SUM(InvoiceTotal) OVER (PARTITION BY VendorID) AS VendorTotal,
    COUNT(InvoiceTotal) OVER (PARTITION BY VendorID) AS VendorCount,
    AVG(InvoiceTotal) OVER (PARTITION BY VendorID) AS VendorAvg
FROM Invoices
20.
SELECT DISTINCT VendorName, COUNT (*) AS NumberofAccounts
FROM Vendors JOIN InvoiceLineItems ON Vendors.DefaultAccountNo = InvoiceLineItems.AccountNo
GROUP BY VendorName
HAVING COUNT (*) > 1
21. SELECT VendorID, SUM(PaymentTotal) AS PaymentSum

FROM Invoices

GROUP BY VendorID;