我想把JSp连接access数据库的代码改写成连接SQL2005数据库的代码，需要改哪里

这是javabean程序，需要改哪里？我改
connect = DriverManager.getConnection(sConnStr,"sa","123456");还是连不上啊  
package vote;
import java.sql.*;

public class VoteConn {
String sDBDriver = "sun.jdbc.odbc.JdbcOdbcDriver";
String sConnStr = "jdbc:odbc:vote";
Connection connect = null;
ResultSet rs = null;
public VoteConn() {
try {
Class.forName(sDBDriver);  
}
catch(java.lang.ClassNotFoundException e) {
System.err.println( e.getMessage());
}
}
public ResultSet executeQuery(String sql) {
try {
connect = DriverManager.getConnection(sConnStr);  
Statement stmt = connect.createStatement();
rs = stmt.executeQuery(sql);
}  
catch(SQLException ex) {  
System.err.println(ex.getMessage());
}
return rs;
}
public int executeUpdate(String sql) {
int result = 0;
try {
connect = DriverManager.getConnection(sConnStr);  
Statement stmt = connect.createStatement();
result = stmt.executeUpdate(sql);
}  
catch(SQLException ex) {  
System.err.println(ex.getMessage());
}
return result;
}	
}
错误信息：
description The server encountered an internal error () that prevented it from fulfilling this request.

exception 

org.apache.jasper.JasperException: java.lang.NullPointerException
	org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:498)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:427)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:320)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

其他：String sDBDriver ="com.microsoft.sqlserver.jdbc.SQLServerDriver"; 这个才是SQL的驱动，至于sConnStr里存放的是什么就不明白了，vote是数据库名吗？把odbc改成sqlserver试一下。分值好诱人啊。。。