Modify the Payroll Program application so it continues to request employee information
until the user enters stop as the employee name. In addition, program the application to
check that the hourly rate and number of hours worked are positive numbers. If either the
hourly rate or the number of hours worked is not a positive value, the application should
prompt the user to enter a positive amount.
I would like to stick to as basic of program as possible. I am not sure if I used the while and if statements correct.© BrainMass Inc. brainmass.com October 24, 2018, 10:43 pm ad1c9bdddf
There are two issues here. First, the compilation problem is due to a simple typo. If you look around line 34 in the program you will see "System.outprint". Notice that the "." between "out" and "print" is missing if you add that "." ...
In this solution I show how to use a while loop to continue to query the user for input until the user enters "stop". This is an addition to a Java payroll program that asks the user to enter employee names, pay rates, and hours. The program calculates the weekly pay for the given employee.
Key benefit provided by the relational model over previous data
1. What is the key benefit provided by the relational model over previous data models?
2. What are three types of physical data dependence described by Codd in his paper?
3. What are the good/bad choices the first two RDB systems made?
4. How the two systems finally united to the current relational database systems. Think about query language, system model, choices on storage, index, query evaluation, etc. What do you think are the choices made in commercial database, why? (Consider 80/20 rule).
5. Use the cost formula to explain why blocked access or pre-fetching is good exercise.
6. Considering a join operation between two tables, one M pages, another N pages, running on a buffer pool with K pages. What is the number of I/Os using nested-loop join, block-nested loop join. What if a hot set algorithm is used or the DBMIN algorithm is used? What if the replacement policy is LRU or MRU?
7. Consider a 3-level tree structure index with maximum 64 entries per internal node. On a range query that retrieve 1000-1200 entries. What is the number of I/Os if the index is B-tree. What is the number of I/Os if the index is B+ tree. What is the number of I/Os if the index is a cluster index?
8. We say that the basic idea behind index is partition and labeling. What is the partition and labeling of a trie structure?
9. write the exhaustive node-split algorithm for R-tree, then analyze the complexity of the algorithm
10. Analyze the complexity of the node-split algorithms in the R*-tree paper. Compare the algorithms to the corresponding ones in the R-tree paper, illustrate under what circumstance the algorithms in the R*-tree paper will out-perform the ones in the R-tree paper, and under what circumstance they will not.
11. In a Z-curve on a 1024 x 1024 grid, the point with coordinates (1,1) is first, the point (1,2) is second, the point (2,1) is third, and so on. What are the coordinates of the 45th point? Of the 17,945th point?
12. Given you a set of nodes (in 2D space), that belongs to one R-tree node that is to be splitted, what is the results of the splitting, using the three algorithms (as presented in the R-tree paper) respectively?
13. Consider a scenario in which we want to use GIST to model the string matching operation, where containment relationship is a fussy sub-string (with gaps). Please specify what the key functions should be defined.
14. Given a table that has 10 columns, 100K tuples expended across 1000 pages, if we project on two columns, with duplicate elimination, and assume that there are 50 unique values on the combination of the two columns, what is number of I/Os in the best/worse cases?
15. Given two tables R1 and R2, one has 1000 tuples, 100 pages, the other has 2000 tuples, 20 pages. Perform join on the two tables with predicate "R1.a > 2 and R1.a = R2.b", what join algorithm will you use, if (1) there is no index at all. (2) there is B+ tree index on R1.a (3) there is B+ tree index on R2.b. (4) there is cluster B+ tree index on R1.a. (5) there is join index on R1.a and R2.b.
16. What does an operator do in the "open" phase? Consider operator sort, nested-loop join, block-nested-loop join, file scan, index scan.
17. What are the possible physical operator(s) that implement a join? Which are blocked, which are pipelined?
18. Give an example of ((A join B) join C) where the output of a sort-merge join for (A join B) can be fed as input to a simple merge join with C, with no intermediate sorting required. A,B,C are relations -- you pick the attributes and the join conditions to make the above example work out.
19. You have a database with a primary index on ID for Employee and Dept, and secondary index on Name for the Employee relation only. You have access methods available for a Nested Loops Join, Nested Indexed Loop Join, and a Grace Hash Join. Generate alternative plans for the following query:
FROM Employee E, Dept D
WHERE E.Dept = D.ID
AND D.Name = "Toys"
20. If you are to design an application-style benchmark for a text-oriented XML database, how would you configure the data set and what are the queries you may ask?