Appendix B: Example JDBC Programs

B.1     Using SELECT

import java.net.URL;

import java.sql.*;

class Select {

	 public static void main(String argv[]) {

		try {

			// Create a URL specifying an ODBC data source name.

			String url = "jdbc:odbc:wombat";

			// Connect to the database at that URL.

			Connection con = DriverManager.getConnection(url, "kgh", "");

			// Execute a SELECT statement

			Statement stmt = con.createStatement();

			ResultSet rs = stmt.executeQuery("SELECT a, b, c, d, key FROM Table1");

			// Step through the result rows.

			System.out.println("Got results:");

			while (rs.next()) {

				// get the values from the current row:

			    	int a = rs.getInt(1);

				BigDecimal b = rs.getBigDecimal(2);

				char c[] = rs.getString(3).tocharArray();

				boolean d = rs.getBoolean(4);

				String key = rs.getString(5);

				// Now print out the results:

				System.out.print("  key=" + key);

				System.out.print("  a=" + a);

				System.out.print("  b=" + b);

				System.out.print("  c=");

				for (int i = 0; i < c.length; i++) {

					System.out.print(c[i]);

				}

				System.out.print("  d=" + d);

				System.out.print("\n");

			}

			stmt.close();

			con.close();

		} catch (java.lang.Exception ex) {

			ex.printStackTrace();

		}

	 }

}

B.2     Using UPDATE

// Update a couple of rows in a database.

import java.net.URL;

import java.sql.*;

class Update {

	public static void main(String argv[]) {

		try {

			// Create a URL specifying an ODBC data source name.

			String url = "jdbc:odbc:wombat";

			// Connect to the database at that URL.

			Connection con = DriverManager.getConnection(url, "kgh", "");

			// Create a prepared statement to update the "a" field of a

			// row in the "Table1" table.

			// The prepared statement takes two parameters.

			PreparedStatement stmt = con.prepareStatement(

						"UPDATE Table1 SET a = ? WHERE key = ?");

			// First use the prepared statement to update 

			// the "count" row to 34.

			stmt.setInt(1, 34);

			stmt.setString(2, "count");

			stmt.executeUpdate();

			System.out.println("Updated \"count\" row OK.");

			// Now use the same prepared statement to update the

			// "mirror" field.

			// We rebind parameter 2, but reuse the other parameter.

			stmt.setString(2, "mirror");

			stmt.executeUpdate();

			System.out.println("Updated \"mirror\" row OK.");

			stmt.close();

			con.close();

		} catch (java.lang.Exception ex) {

			ex.printStackTrace();

		}

	}

}

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