User Level Commands
Find (ID) {Private Operation - not Exported} Searches for the record with specified ID number in the Data_Base. It returns where the search terminates (either successfully or not successfully finding).
D(elete) (ID) -deletes the record with specified ID number from the DB.
E(xit) -exit the DB system.
I(nsert) (Emp_Rec) -inserts the specified employee record into the DB.
S(how) (ID) -displays the record with the specified ID number (or an error message).
T(raverse) (ID, Count, Direction) - displays Count records beginning with the specified ID, traversing either forward or backward as specified by the direction. Traverse must start by first searching for ID and then commences the traversal from the node returned by the search method.
The idea in the commands is to differentiate between two kinds of "users" of your program: a database administrator and the end user of the database.
Specifically, a DB admin would Create, get STATus of the DB and allow for a command to Read files of commands.
(High level DB actions – that a “user” would not be allowed to do)
Whereas a User would have the commands to add and get domain information from the DB (to Find things, Delete things, Insert things, Exit, Show certain things,
and Traverse through for a certain range of records.) (Low level access actions)
The application should differentiate between
The DB records are accessed through tree nodes that contain only access/handles
(used to say "pointers") to the records and to other tree nodes or NIL.
The data base is implemented by using a B-tree
and allows traversals to commence at a
specified node. Some details about
the B-tree are given below.
A top-level class should itself contain (or have an auxiliary class which contains) a loop to read the allowed user commands (both admin and end-user) and their
parameters from a specified file using a command interpreter. You may, if you wish, also allow a user to input single commands at a time
(this might help you with debugging.)
The command interpreter should send input of the
allowed commands to the proper USER INTERFACE modules. The methods therein will then make the proper calls to the database.
DELIVERABLES
Verify the correct operation of the DB system by executing the data file
called lab3.data (formally btree.dat).
Located at http://www.ecst.csuchico.edu/~amk/foo/csci311/labs/lab3/lab3.data
The documentation for this assignment should include the structure chart
for the DB ADT implementation, the ADT specs, and of course normal program
documentation.
[1] internal path length:
the sum over all internal nodes of the lengths of the
paths from the root to those nodes.
Finally
If you use a parent node in the tree node class, make sure to address the issue of why it was needed. If it was not really needed but used for convenience (easier to code than keeping track of all of the cases) OR you felt using them was a better programming strategy, be explicit about your reasoning in your documentation.
DATA BASE IMPLEMENTATION
Suggested declarations:
Class
Emp_Rec
IVs:
ID_# :1..999; {Has unique identification property}
Name : Name_Type;
Phone : Phone_Type; {Optional}
Salary : Real {Optional}{5000 - 100,000 dollars}
Node
IVs:
Left_Data, Right_Data : Emp_Rec;
Left_Link, Middle_Link, Right_Link : Node;
PROGRAM ORGANIZATION
Specifically, the UI classes
are separate from the class that implements the specified DB ADT.
The DB ADT contains 
External path length is the sum over all external nodes of the lengths of the paths from the root to those nodes. Above would be
2 + 2 + 4 + 4 + 3 + 2 = 17