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package example.corba;
import java.sql.*;
/*
* This class handles the JDBC side of things. It opens a connection to
* the database, and performes queries on that database.
*
* In essence, you could use this class on it's own. The rest of the classes
* in this example handle either the CORBA mechanism, or the frontend.
*
* Note: Before you ask, why perform a query on each call, you have to remember
* that an object could be changed by another client, and we need to ensure that
* the returned data is live and accurate.
*
* $Id: StockDB.java,v 1.4 2001/11/19 22:43:13 momjian Exp $
*/
public class StockDB
{
Connection con;
Statement st;
// the current stock number
int id = -1;
public void connect(String url, String usr, String pwd) throws Exception
{
Class.forName("org.postgresql.Driver");
System.out.println("Connecting to " + url);
con = DriverManager.getConnection(url, usr, pwd);
st = con.createStatement();
}
public void closeConnection() throws Exception
{
con.close();
}
public void fetchItem(int id) throws Exception
{
this.id = id;
}
public int newItem() throws Exception
{
// tba
return -1;
}
public String getDescription() throws SQLException
{
ResultSet rs = st.executeQuery("select description from stock where id=" + id);
if (rs != null)
{
rs.next();
String s = rs.getString(1);
rs.close();
return s;
}
throw new SQLException("No ResultSet");
}
public int getAvailable() throws SQLException
{
ResultSet rs = st.executeQuery("select avail from stock where id=" + id);
if (rs != null)
{
rs.next();
int v = rs.getInt(1);
rs.close();
return v;
}
throw new SQLException("No ResultSet");
}
public int getOrdered() throws SQLException
{
ResultSet rs = st.executeQuery("select ordered from stock where id=" + id);
if (rs != null)
{
rs.next();
int v = rs.getInt(1);
rs.close();
return v;
}
throw new SQLException("No ResultSet");
}
public boolean isItemValid() throws SQLException
{
ResultSet rs = st.executeQuery("select valid from stock where id=" + id);
if (rs != null)
{
rs.next();
boolean b = rs.getBoolean(1);
rs.close();
return b;
}
throw new SQLException("No ResultSet");
}
public void addNewStock(int amount) throws SQLException
{
st.executeUpdate("update stock set avail=avail+" + amount +
", ordered=ordered-" + amount +
" where id=" + id + " and ordered>=" + amount);
}
public void removeStock(int amount) throws SQLException
{
st.executeUpdate("update stock set avail=avail-" + amount +
" where id=" + id);
}
public void orderStock(int amount) throws SQLException
{
st.executeUpdate("update stock set ordered=ordered+" + amount +
" where id=" + id);
}
public int getLastID() throws SQLException
{
ResultSet rs = st.executeQuery("select max(id) from stock");
if (rs != null)
{
rs.next();
int v = rs.getInt(1);
rs.close();
return v;
}
throw new SQLException("No ResultSet");
}
}
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