Write a SELECT statement that returns four columns based on the InvoiceTotal column of the Invoices table: A. Use the CAST function to return the first column as data type decimal with 2 digits to the right of the decimal point. B. Use CAST to return the second column as a varchar. C. Use the CONVERT function to return the third column as the same data type as the first column. D. Use CONVERT to return the fourth column as a varchar, using style 1.

Write a method named addall that could be placed inside the hashintset class. this method accepts another hashintset as a parameter and adds all elements from that set into the current set, if they are not already present. for example, if a set s1 contains [1, 2, 3] and another set s2 contains [1, 7, 3, 9], the call of s1.addall(s2); would change s1 to store [1, 2, 3, 7, 9] in some order. you are allowed to call methods on your set and/or the other set. do not modify the set passed in. this method should run in o(n) time where n is the number of elements in the parameter set passed in.