// modified from [CIS 318] Lab6.java, written by Ann Burroughs
//
// ask users to tell you which column of the emp
// table they want, then build a query with that
// column and display it
//
// modified by: Sharon Tuttle
// last modified: 4-16-01

import java.sql.*;
import java.io.*;

public class AskForCol
{
	public static void main(String args[])
	{
		Statement	myStmt;
		ResultSet	myRS;
		String		response, myQ, rowToPrint;
		BufferedReader  in;
		int		colCode = 0;

		String[] colNames = {"empno", "ename", "job", "mgr",
			             "hiredate", "sal", "comm", "deptno"};

		try
		{	
			// load JDBC driver and set up db connection
                        Class.forName("oracle.jdbc.driver.OracleDriver");
                        Connection con = DriverManager.getConnection
                                ("jdbc:oracle:thin:@redwood:1521:student",
                                 "java", "java");

                        // declare and create a statement object
                        myStmt = con.createStatement();

			// this local method prints a list of
			// column choices for the user
			printColChoices();			
			System.out.println("");

			// ask the user which column they wish to see
			System.out.println("Type the integer of a " +
					   "desired column: ");
			System.out.flush();

			in = new BufferedReader(new InputStreamReader(
				System.in));
			response = in.readLine();
			response = response.trim(); // trim white space
			try
			{
				// subtract 1 because array indices are 0-7
				colCode = Integer.parseInt(response) - 1;
				if ((colCode < 0) || (colCode > 7))
				{
					System.out.println("AskForCols: " +
					   "column out of range --- not" +
					   " between 1-8: " + response);
					myStmt.close();
					con.close();
					System.exit(0);
				}
			}
			catch(NumberFormatException exc)
			{
				System.out.println("AskForCols: bad " +
					"column --- not between 1-8: " +
					response);
				myStmt.close();
				con.close();
				System.exit(0);
			}

			// whew! I have a good column, at this point
			myQ = "select " + colNames[colCode] +
			      " from emp";

			myRS = myStmt.executeQuery(myQ);

			System.out.println(colNames[colCode]);
			System.out.println("-----------------------");
			while (myRS.next() != false)
			{
				// hmm --- what does this do to non-strings?
				// (seems mostly reasonable, but note that
				// you get the string "null" for a null
				// value...!
				rowToPrint = myRS.getString(colNames[colCode]);
								
				System.out.println(rowToPrint);
			}
			System.out.println("-----------------------");

			// close statement and connection!
			myStmt.close();
			con.close();
		}
		catch (Exception exc)
		{
			System.out.println("AskForCol: " +  exc.getMessage());
		}
	}
				
	// this simply prints out a "menu" of column
	// choices for the user to choose from
	private static void printColChoices()
	{
		System.out.println("------------------------------");
		System.out.println("Choose which column you wish:");
		System.out.println("------------------------------");
		System.out.println("1. empno");
		System.out.println("2. ename");
		System.out.println("3. job");
		System.out.println("4. mgr");
		System.out.println("5. hiredate");
		System.out.println("6. sal");
		System.out.println("7. comm");
		System.out.println("8. deptno");
		System.out.println("------------------------------");
	}

}