分享一段php、mysql操作类的代码，供初学的朋友参考。
一个简单的类使用php和mysql数据库连接类，代码：

<?php 
/**
* php、mysql连接类
* by www.
*/
//----
/*
include "database.php"; //数据库配置信息

$db_host="localhost"; 
$db_user="user"; 
$db_pass="user"; 

$username=$_POST["txtUserName"]; 
$password=$_POST["txtPassword"]; 

$dbobj=new db; 
$dbobj->db_connect($db_host, $db_user, $db_pass,$db_name); 
$query="insert db_user values('$username','$password')"; 
$result=$dbobj->db_updateData($query); 
*/ 

class db 
{ 

var $query; 
var $numrows; 
  function db_connect($db_host, $db_user, $db_pass,$db_name)  
  { 
  global $ln; 
  global $result; 

  $db_host1=$db_host; 
  $db_user1=$db_user; 
  $db_pass1=$db_pass; 
  $db_name1=$db_name; 

 $ln = mysql_connect($db_host1, $db_user1, $db_pass1) or die("cannot connect"); 
 mysql_select_db($db_name1,$ln); 
  } 

  function db_selectData($query) 
  { 
global $ln; 
  global $result; 

  $this->query=$query; 
  $result= mysql_query($this->query,$ln); 
  return $result; 
  
  } 

  function db_deleteData($query) 
  { 
  global $ln; 
  global $result; 

 $this->query=$query; 
 $result= mysql_query($this->query,$ln); 
 return $result; 
  } 

  function db_updateData($query) 
  { 
   global $ln; 
 global $result; 
   $this->query=$query; 
 $result= mysql_query($this->query,$ln); 
 return $result; 

  } 

  function db_countRows($res) 
  { 
  global $ln; 
  global $result; 
  $this->numrows = mysql_num_rows($result); 
  return $this->numrows; 
  } 

  function db_close() 
  { 
  global $ln; 
  mysql_close($ln); 
  } 
}
?>

分享一个php与mysql操作类，代码：

<?php
/**
* mysql操作类
* by www.
*/

// 定义常量

/**
 * 是否开启调试模式
 */
define("DEBUG", FALSE);

/**
 * 以下变量不要改动
 */

/**
 * 设定表的读锁
 */
define("LOCKED_FOR_READ", "READ");
/**
 * 设定表的写锁
 */
define("LOCKED_FOR_WRITE", "WRITE");

/**
 * HOWTO
 */
class mySQL {

 /**
    * The connection resource id
    *
    * @var  object
    */
 var $connection;

 /**
    * The selected database
    *
    * @var  object
    */
 var $selectedDb;

 /**
    * The result from a select-query
    *
    * @var  object
    */
 var $result;

 /**
    * Flag that tells if you are connected to the database or not
    *
    * @var  boolean
    */
 var $isConnected;

 /**
    * Flag that tells if you the tables are locked or not
    *
    * @var  boolean
    */
 var $isLocked;
 
 /**
  *This will indicate what querytype the last query was
  *
  * @var string
  */
 var $queryType;

 /**
  * This is the constructor of this mysql class.
  * It creates a connection to the database, and if possible it sets the database to
  * You can specify if you want to use persistant connections or not.
  *
  * @param  string The host to the mySQL server
  * @param string The username you use to log on to the mySQL server
  * @param string The password you use to log on to the mySQL server
  * @param string The name of the database you wish to use
  * @param boolean TRUE if you want to use persistant connections. Default is TRUE
  * @return boolean TRUE when connection was successfull
  * @access public
  */ 
 function mySQL($sHost, $sUser, $sPassword, $sDatabase="", $bPersistant=TRUE) {
  $conFunc = "";
  
  if(!defined("DEBUG")) {
   define("DEBUG", FALSE);
  }
  
  if($this->getConnected()) {
   $this->closeConnection();
  }
  if($this->connection = ($bPersistant ? mysql_pconnect($sHost, $sUser, $sPassword) : mysql_connect($sHost, $sUser, $sPassword))) {
   $this->setConnected(TRUE);
   
   if($sDatabase) {
    $this->setDb($sDatabase);
   
   }
   
   return TRUE;
  } else {
   $this->setConnected(FALSE);
   return FALSE;
  }
 }
 
 /**
  * This is the destructor of this class. It frees the result of a query,
  * it unlocks all locked tables and close the connection to the database
  * It does not return anything at all, so you will not know if it was sauccessfull
  *
  * @access public
  */
 function _mySQL() {
  if($this->result) {
   $this->freeResult();
  }
  if($this->getLocked()) {
   $this->unlock();
  }
  if($this->getConnected()) {
   $this->closeConnection();
  }
 }
 
 /**
  * This function frees the result from a query if there is any result.
  *
  * @access public
  */
 function freeResult() {
  if($this->result) {
   @mysql_free_result($this->result);
  }
 }
 
 /**
  * This function executes a query to the database.
  * The function does not return the result of the query, you must call the
  * function getQueryResult() to fetch the result
  *
  * @param  string The query-string to execute
  * @return boolean TRUE if the query was successfull
  * @access public
  */
 function query($query) {
  if(strlen(trim($query)) == 0) {
   $this->printError("No query got in function query()");
   return FALSE;
  }
  if(!$this->getConnected()) {
   $this->printError("Not connected in function query()");
   return FALSE;
  }
  
  $queryType = substr(trim($query), 0, strpos($query, " "));
  $this->setQueryType($queryType);
  
  $this->result = mysql_query($query, $this->connection);
  if($this->result) {
   return TRUE;
  }
  return FALSE;
 }
 
 /**
  * Sets the querytype of the last query executed
  * For example it can be SELECT, UPDATE, DELETE etc.
  *
  * @access private
  */
 function setQueryType($type) {
  $this->queryType = strtoupper($type);
 }
 
 /**
  * Returns the querytype
  *
  * @return string
  * @access private
  */
 function getQueryType() {
  return $this->queryType;
 }
 
 /**
  * This function returns number of rows got when executing a query
  *
  * @return mixed FALSE if there is no query-result.
  *     If the queryType is SELECT then it will use the function MYSQL_NUM_ROWS
  *     Otherwise it uses the MYSQL_AFFECTED_ROWS
  * @access public
  */
 function getNumRows() {
  if($this->result) {
   if(DEBUG==TRUE) {
    print("<font background-color: red\">".$this->getQueryType()."</font><br>");
   }
   return mysql_affected_rows($this->connection);
  }
  return FALSE;
 }
 
 /**
  * The function returns the result from a call to the query() function
  *
  * @return object
  * @access public
  */
 function getQueryResult() {
  return $this->result;
 }
 
 /**
  * This function returns the query result as an array for each row in the query result
  *
  * @return array
  * @access public
  */
 function fetchArray() {
  if($this->result) {
   return mysql_fetch_array($this->result);
  }
  return FALSE;
 }
 
 /**
  * This function returns the query result as an object for each row in the query result
  *
  * @return object
  * @access public
  */
 function fetchObject() {
  if($this->result) {
   return mysql_fetch_object($this->result);
  }
  return FALSE;
 }
 
 /**
  * This function returns the query result as an array for each row in the query result
  *
  * @return array
  * @access public
  */
 function fetchRow() {
  if($this->result) {
   return mysql_fetch_row($this->result);
  }
  return FALSE;
 }
 
 /**
  * This function sets the database
  *
  * @return boolean TRUE if the database was set
  * @access public
  */
 function setDb($sDatabase) {
  if(!$this->getConnected()) {
   $this->printError("Not connected in function setDb()");
   return FALSE;
  }
  if($this->selectedDb = mysql_select_db($sDatabase, $this->connection)) {
   return TRUE;
  }
  return FALSE;
 }
 
 /**
  * This function returns a flag so you can see if you are connected to the database
  * or not
  *
  * @return boolean TRUE when connected to the database
  * @access public
  */
 function getConnected() {
  return $this->isConnected;
 }

 /**
  * This function sets the flag so you can see if you are connected to the database
  *
  * @param $bStatus The status of the connection. TRUE if you are connected,
  *      FALSE if you are not
  * @access public
  */
 function setConnected($bStatus) {
  $this->isConnected = $bStatus;
 }
 
 /**
  * The function unlocks tables if there are locked tables and the closes the
  * connection to the database.
  *
  * @access public
  */
 function closeConnection() {
  if($this->getLocked()) {
   $this->unlock();
  }
  
  if($this->getConnected()) {
   mysql_close($this->connection);
   $this->setConnected(FALSE);
  }
 }
 
 /**
  * Unlocks all tables that are locked
  *
  * @access public
  */
 function unlock() {
  if(!$this->getConnected()) {
   $this->setLocked(FALSE);
  }   
  if($this->getLocked()) {
   $this->query("UNLOCK TABLES"); 
   $this->setLocked(FALSE);
  }
 }

 /**
  * This function locks the table(s) that you specify
  * The type of lock must be specified at the end of the string.
  *
  * @param string a string containing the table(s) to lock, 
  *     as well as the type of lock to use (READ or WRITE) 
  *     at the end of the string
  * @return boolean TRUE if the tables was successfully locked
  * @access private
  */
 function lock($sCommand) {
  if($this->query("LOCK TABLE ".$sCommand)) {
   $this->setLocked(TRUE);
   return TRUE;
  }
  
  $this->setLocked(FALSE);
  return FALSE;
 }
 
 /**
  * This functions sets read lock to specified table(s)
  *
  * @param string a string containing the table(s) to read-lock
  * @return boolean TRUE on success
  */
 function setReadLock($sTable) {
  return $this->lock($sTable." ".LOCKED_FOR_READ);
 }
 
 /**
  * This functions sets write lock to specified table(s)
  *
  * @param string a string containing the table(s) to read-lock
  * @return boolean TRUE on success
  */
 function setWriteLock($sTable) {
  return $this->lock($sTable." ".LOCKED_FOR_WRITE);
 }
  
 /**
  * Sets the flag that indicates if there is any tables locked
  *
  * @param boolean The flag that will indicate the lock. TRUE if locked
  */
 function setLocked($bStatus) {
  $this->isLocked = $bStatus;
 }
 
 /**
  * Returns TRUE if there is any locked tables
  *
  * @return boolean TRUE if there are locked tables
  */
 function getLocked() {
  return $this->isLocked;
 }

 /**
  * Prints an error to the screen. Can be used to kill the application
  *
  * @param string The text to display
  * @param boolean TRUE if you want to kill the application. Default is FALSE
  */
 function printError($text, $killApp=FALSE) {
  if($text) {
   print("<b>Error</b><br />".$text);
  }
  if($killApp) {
   exit();
  }
 }
 
 /**
  * Display any mysql-error
  *
  * @return mixed String with the error if there is any error.
  *     Otherwise it returns FALSE
  */
 function getMysqlError() {
  if(mysql_error()) {
   return "<br /><b>Mysql Error Number ".mysql_errno()."</b><br />".mysql_error();
  }
  return FALSE;
 }
}
?>

代码：

<?php 
/**
* desc：mysql操作类
* filename:db.class.php
* by www.
*/
 
Class db
{
//数据库配置信息
private $Host='localhost';
private $UserName='root';
private $Password='';
private $DbName='dbname';
//根据自己的实际情况修改

public  $link;
public $query;
public $last_error;

function __construct()
{    
   $this->Connect();
}
function __destruct()
{
   $this->Close();
}
private function Connect()
{
   //数据库连接
   $this->link=mysql_connect($this->Host,$this->UserName,$this->Password) or die("Error Connect to DB");
   $this->SetError(mysql_error());
   //select db ...
   mysql_select_db($this->DbName) ;//or die("Error Select DB");
   $this->SetError(mysql_error());
}

public function query($query)
{
 //mysql查询
 $this->query=mysql_query($query,$this->link);
 $this->SetError(mysql_error());
}
    
public function assoc()
{
   //mysql_fetch_assoc :
   return mysql_fetch_assoc($this->query);
   $this->SetError(mysql_error());
}

public function num()
{
   //mysql_num_rows:
   return mysql_num_rows($this->query);
   $this->SetError(mysql_error());
}
    
public function result($index=0)
{
   //mysql_result : 
   return mysql_result($this->query,$index);
   $this->SetError(mysql_error());
}
    
private function SetError($error)
{
  $this->last_error=$error;
}

public function ShowError()
{
   return $this->last_error;
}

private function Close()
{
  mysql_close($this->link);
}
}
?>

调用示例：

<?php
// include class : 
require_once "db.class.php"; 

//creat a db object 
$con=new db; 

//run the query: 
$con->query("select * from table "); 

//get number of result 
echo $con->num() . PHP_EOL; 

//get result 
echo $con->result(/* $index */) . PHP_EOL; 

//get all result 
while($row=$con->assoc()) var_dump($row);