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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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