java02_main.java

Primary and Foreign-key reference. Two table types, second referencing the first.

import java.sql.*;
public class java02_main {
/*
* EXAMPLE SQL02 for JDBC
* When you run this example, a new database is created with two tables
* where one references the other. Then a single row is created in the
* referenced table and four rows are created in the referencing table.
* Finally all the data is read from the database using a join.
*
* Full documentation for RDM is available at http://docs.raima.com/rdm/
*
* For simplicity this example utilizes basic exception handling
* but good programming practices would dictate that this occur in
* a full application.
*/
public static void main(String[] args) throws SQLException {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try
{
/* Create the connection with a simple connection string */
conn = DriverManager.getConnection("jdbc:raima:rdm://local");
conn.setAutoCommit(true);
CreateDatabase(conn);
/* Open the connection to the database */
stmt = conn.createStatement();
/* Insert a row into the referenced table */
stmt.executeUpdate("INSERT INTO PriTab Values 1,'referenced 1'");
/* Insert four rows into the referenced table */
for (int ii = 1; ii < 5; ii++)
{
stmt.executeUpdate("INSERT INTO ForTab VALUES 'referencing " + ii + "', 1");
}
/* Scan through all the existing rows using a join and display the contents */
rs = stmt.executeQuery("SELECT pstr, fstr FROM ForTab, PriTab where ForTab.pid = PriTab.pid");
while (rs.next() != false)
{
System.out.println(rs.getString(1) + " -- " + rs.getString(2));
}
}
catch (SQLException sqle)
{
sqle.printStackTrace();
}
finally
{
if(rs != null)
rs.close();
if(stmt != null)
stmt.close();
if(conn != null)
conn.close();
}
}
private static void CreateDatabase(Connection conn)
{
Statement stmt = null;
try
{
/* Create the example database */
stmt = conn.createStatement();
/* Since the database is created here, it cannot be created twice */
try {
stmt.executeUpdate("DROP DATABASE java02");
} catch (SQLException sqle) {}
stmt.execute("CREATE DATABASE java02");
stmt.execute("CREATE TABLE PriTab (pid INTEGER PRIMARY KEY, pstr CHAR(30))");
stmt.execute("CREATE TABLE ForTab (fstr CHAR(30), pid INTEGER REFERENCES PriTab(pid))");
conn.commit();
stmt.close();
stmt = null;
}
catch (SQLException sqle)
{
sqle.printStackTrace();
}
}
}