Cut from: http://www.oschina.net/code/snippet_96541_3441

Db class for PHP

<?phpClass DB {private $link_id;private $handle;private $is_log;private $time;//构造函数public function __construct() {$this->time = $this->microtime_float();require_once("config.db.php");$this->connect($db_config["hostname"], $db_config["username"], $db_config["password"], $db_config["database"], $db_config["pconnect"]);$this->is_log = $db_config["log"];if($this->is_log){$handle = fopen($db_config["logfilepath"]."dblog.txt", "a+");$this->handle=$handle;}}//数据库连接public function connect($dbhost, $dbuser, $dbpw, $dbname, $pconnect = 0,$charset='utf8') {if( $pconnect==0 ) {$this->link_id = @mysql_connect($dbhost, $dbuser, $dbpw, true);if(!$this->link_id){$this->halt("数据库连接失败");}} else {$this->link_id = @mysql_pconnect($dbhost, $dbuser, $dbpw);if(!$this->link_id){$this->halt("数据库持久连接失败");}}if(!@mysql_select_db($dbname,$this->link_id)) {$this->halt('数据库选择失败');}@mysql_query("set names ".$charset);}//查询 public function query($sql) {$this->write_log("查询 ".$sql);$query = mysql_query($sql,$this->link_id);if(!$query) $this->halt('Query Error: ' . $sql);return $query;}//获取一条记录（MYSQL_ASSOC，MYSQL_NUM，MYSQL_BOTH）public function get_one($sql,$result_type = MYSQL_ASSOC) {$query = $this->query($sql);$rt =& mysql_fetch_array($query,$result_type);$this->write_log("获取一条记录 ".$sql);return $rt;}//获取全部记录public function get_all($sql,$result_type = MYSQL_ASSOC) {$query = $this->query($sql);$i = 0;$rt = array();while($row =& mysql_fetch_array($query,$result_type)) {$rt[$i]=$row;$i++;}$this->write_log("获取全部记录 ".$sql);return $rt;}//插入public function insert($table,$dataArray) {$field = "";$value = "";if( !is_array($dataArray) || count($dataArray)<=0) {$this->halt('没有要插入的数据');return false;}while(list($key,$val)=each($dataArray)) {$field .="$key,";$value .="'$val',";}$field = substr( $field,0,-1);$value = substr( $value,0,-1);$sql = "insert into $table($field) values($value)";$this->write_log("插入 ".$sql);if(!$this->query($sql)) return false;return true;}//更新public function update( $table,$dataArray,$condition="") {if( !is_array($dataArray) || count($dataArray)<=0) {$this->halt('没有要更新的数据');return false;}$value = "";while( list($key,$val) = each($dataArray))$value .= "$key = '$val',";$value .= substr( $value,0,-1);$sql = "update $table set $value where 1=1 and $condition";$this->write_log("更新 ".$sql);if(!$this->query($sql)) return false;return true;}//删除public function delete( $table,$condition="") {if( empty($condition) ) {$this->halt('没有设置删除的条件');return false;}$sql = "delete from $table where 1=1 and $condition";$this->write_log("删除 ".$sql);if(!$this->query($sql)) return false;return true;}//返回结果集public function fetch_array($query, $result_type = MYSQL_ASSOC){$this->write_log("返回结果集");return mysql_fetch_array($query, $result_type);}//获取记录条数public function num_rows($results) {if(!is_bool($results)) {$num = mysql_num_rows($results);$this->write_log("获取的记录条数为".$num);return $num;} else {return 0;}}//释放结果集public function free_result() {$void = func_get_args();foreach($void as $query) {if(is_resource($query) && get_resource_type($query) === 'mysql result') {return mysql_free_result($query);}}$this->write_log("释放结果集");}//获取最后插入的idpublic function insert_id() {$id = mysql_insert_id($this->link_id);$this->write_log("最后插入的id为".$id);return $id;}//关闭数据库连接protected function close() {$this->write_log("已关闭数据库连接");return @mysql_close($this->link_id);}//错误提示private function halt($msg='') {$msg .= "\r\n".mysql_error();$this->write_log($msg);die($msg);}//析构函数public function __destruct() {$this->free_result();$use_time = ($this-> microtime_float())-($this->time);$this->write_log("完成整个查询任务,所用时间为".$use_time);if($this->is_log){fclose($this->handle);}}//写入日志文件public function write_log($msg=''){if($this->is_log){$text = date("Y-m-d H:i:s")." ".$msg."\r\n";fwrite($this->handle,$text);}}//获取毫秒数public function microtime_float() {list($usec, $sec) = explode(" ", microtime());return ((float)$usec + (float)$sec);}}?>