怎么样连接数据库阿！！！有没有好的教程或实例阿

Question

conn.jsp
<%
String sDBDriver = "COM.ibm.db2.jdbc.app.DB2Driver";
String sConnStr = "jdbc:db2:faq";
Connection conn = null;
Statement stmt = null;
ResultSet rs=null;
try {
Class.forName(sDBDriver); 
}
catch(java.lang.ClassNotFoundException e) {
out.print("faq(): " + e.getMessage());
}try{
conn = DriverManager.getConnection(sConnStr,"wsdemo","wsdemo1"); 
stmt = conn.createStatement();
}catch(SQLException e){
out.print(e.toString());
}
%>query.jsp<%@ page language="java" import="java.sql.*" %>
<%@ page contentType="text/html; charset=gb2312" %>
<%@ include file="conn.jsp" %>
<%
......
int pages=0;
int pagesize=10;
ResultSet result = null;
ResultSet rcount = null;pages = new Integer(request.getParameter("pages")).intValue();if (pages>0)
{String sql=" state='我不傻'";
int count=0;
try {
rcount = stmt.executeQuery("SELECT count(id) as id from user where "+sql);
catch(SQLException ex) {
out.print("aq.executeQuery: " + ex.getMessage());
}
if(rcount.next())
count = rcount.getInt("id");
rcount.close();
if (count>0)
{
sql="select * from user where "+sql;
try {
result = stmt.executeQuery(sql);
}
catch(SQLException ex) {
out.print("aq.executeQuery: " + ex.getMessage());
}
int i;
String name;
// result.first();
// result.absolute((pages-1)*pagesize);
// 此方法jdbc2.0支持。编译通过，但执行不过，不知是不是跟驱动有关，只好用下面的笨办法。
for(i=1;i<=(pages-1)*pagesize;i++)
result.next();
for(i=1;i<=pagesize;i++) {
if (result.next()) {
name=result.getString("name");
out.print(name);
}
result.close();
int n= (int)(count/pagesize);
if (n*pagesize<count) n++;
if (n>1)
{for(i=1;i<=n;i++)
out.print("<a href=query.jsp?pages="+i+">"+i+"&nbsp;</a>"); } } } %> 
 

Answer 1

/*
/*@ author:yjx
/*@ date:2001-7-9
*//*import package file*/
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.sql.*;
import java.util.*;
import java.lang.*;public class Loginservlet extends HttpServlet
{
public void doPost(HttpServletRequest req,
                    HttpServletResponse resp)
    throws ServletException,java.io.IOException
    {
PrintWriter out;
String          strUserName,strPWD;
String          strDBDriver,strURL;
String          strSQL,strTemp;
Connection      conn=null;
Statement       stmt=null;
ResultSet       rs=null;
int             iExist=0;//0:not exits,1:exits
HttpSession     session; session=req.getSession();
        out = resp.getWriter(); //get parameters
strUserName=req.getParameter("username");
     strPWD=req.getParameter("password");        //set database connection parameter value
strDBDriver="sun.jdbc.odbc.JdbcOdbcDriver";
strURL="jdbc:odbc:wygl";        if(strUserName!=null || strUserName.compareTo("")!=0){
//instance session variable：
session.putValue("login_name","");
session.putValue("user_name","");
session.putValue("dept_id","");
session.putValue("duty","");
session.putValue("mright","");
session.putValue("uitype","");
session.putValue("logined","false");
session.putValue("info","null");
    
//connect database
try{
Class.forName(strDBDriver);
}catch(java.lang.ClassNotFoundException e){
System.err.println("error:"+e.getMessage());
} try{
conn=DriverManager.getConnection(strURL);
stmt=conn.createStatement();
}catch(SQLException e){
System.out.println("error:"+e.getMessage());
}
            strSQL="select * from sys_user where login_name='"+strUserName+"' and user_pwd='"+strPWD+"'"; try{
rs=stmt.executeQuery(strSQL);
if(rs.next()){
session.putValue("login_name",strUserName); session.putValue("logined","true"); strTemp=rs.getString("user_name");
session.putValue("user_name",strTemp); strTemp=rs.getString("dept_id");
session.putValue("dept_id",strTemp);

strTemp=rs.getString("duty");
session.putValue("duty",strTemp); strTemp=rs.getString("mright");
session.putValue("mright",strTemp); strTemp=rs.getString("uitype");
session.putValue("uitype",strTemp); resp.sendRedirect("/wygl/jsp/sysindex.jsp");
}else{
resp.sendRedirect("/wygl/jsp/errorindex.jsp");
}
}catch(SQLException e){
System.err.println("error:"+e.getMessage());
}
}
}
}

Answer 2

另外一个例子：
/*
* @dbbean.java
* Author:nicolas
* Date:2001-3-21
* version:1.0v
* Function:connect database,query table,update table by parameter
*/
package dbbean;
import java.sql.*;
import java.io.*;public class dbbean{
//String sConnStr="jdbc:oracle:thin:@172.16.1.2:1521:labora","scott","tiger";
String sDBDriver="sun.jdbc.odbc.JdbcOdbcDriver";
Connection conn=null;
ResultSet rs=null;
    
/*
    * constructor:try to create a dababase driver
  */
public dbbean(){
try{
Class.forName(sDBDriver);
}catch(java.lang.ClassNotFoundException e){
System.err.println("dbbean():  "+e.getMessage());
}
} public ResultSet executeQuery(String sqlStr){
rs=null;
try{
conn=DriverManager.getConnection("jdbc:odbc:wygl");
Statement stmt=conn.createStatement();
rs=stmt.executeQuery(sqlStr);
}catch(SQLException e){
System.err.println("executeQuery():  "+e.getMessage());
}
return rs;
} public int executeInsert(String sqlStr){
try{
conn=DriverManager.getConnection("jdbc:odbc:wygl");
Statement stmt=conn.createStatement();
stmt.executeUpdate(sqlStr);
return 1;//成功
}catch(SQLException e){
System.err.println("executeInsert():  "+e.getMessage());
return 0;//失败
}
}    public int executeUpdate(String sqlStr){
try{
conn=DriverManager.getConnection("jdbc:odbc:wygl");
Statement stmt=conn.createStatement();
stmt.executeUpdate(sqlStr);
return 1;//成功
}catch(SQLException e){
System.err.println("executeInsert():  "+e.getMessage());
return 0;//失败
}
} public int executeDelete(String sqlStr){
try{
conn=DriverManager.getConnection("jdbc:odbc:wygl");
Statement stmt=conn.createStatement();
stmt.executeUpdate(sqlStr);
return 1;//成功
}catch(SQLException e){
System.err.println("executeDelete():  "+e.getMessage());
return 0;//失败
}
}
}

Answer 3

另外一个例子：
/*
* @dbbean.java
* Author:nicolas
* Date:2001-3-21
* version:1.0v
* Function:connect database,query table,update table by parameter
*/
package dbbean;
import java.sql.*;
import java.io.*;public class dbbean{
//String sConnStr="jdbc:oracle:thin:@172.16.1.2:1521:labora","scott","tiger";
String sDBDriver="sun.jdbc.odbc.JdbcOdbcDriver";
Connection conn=null;
ResultSet rs=null;
    
/*
    * constructor:try to create a dababase driver
  */
public dbbean(){
try{
Class.forName(sDBDriver);
}catch(java.lang.ClassNotFoundException e){
System.err.println("dbbean():  "+e.getMessage());
}
} public ResultSet executeQuery(String sqlStr){
rs=null;
try{
conn=DriverManager.getConnection("jdbc:odbc:wygl");
Statement stmt=conn.createStatement();
rs=stmt.executeQuery(sqlStr);
}catch(SQLException e){
System.err.println("executeQuery():  "+e.getMessage());
}
return rs;
} public int executeInsert(String sqlStr){
try{
conn=DriverManager.getConnection("jdbc:odbc:wygl");
Statement stmt=conn.createStatement();
stmt.executeUpdate(sqlStr);
return 1;//成功
}catch(SQLException e){
System.err.println("executeInsert():  "+e.getMessage());
return 0;//失败
}
}    public int executeUpdate(String sqlStr){
try{
conn=DriverManager.getConnection("jdbc:odbc:wygl");
Statement stmt=conn.createStatement();
stmt.executeUpdate(sqlStr);
return 1;//成功
}catch(SQLException e){
System.err.println("executeInsert():  "+e.getMessage());
return 0;//失败
}
} public int executeDelete(String sqlStr){
try{
conn=DriverManager.getConnection("jdbc:odbc:wygl");
Statement stmt=conn.createStatement();
stmt.executeUpdate(sqlStr);
return 1;//成功
}catch(SQLException e){
System.err.println("executeDelete():  "+e.getMessage());
return 0;//失败
}
}
}