PHP单例模式简单用法示例


            本文实例讲述了PHP单例模式用法。分享给大家供大家参考，具体如下：





<?php

class db {

  public $conn;

  public static $sql;

  public static $instance=null;

  private function __construct(){

    require_once('db.config.php');

    $this->conn = mysql_connect($db['host'],$db['user'],$db['password']);

    if(!mysql_select_db($db['database'],$this->conn)){

      echo "失败";

    };

    mysql_query('set names utf8',$this->conn);

  }

  public static function getInstance(){

  if(is_null(self::$instance)){

    self::$instance = new self();

  }

    return self::$instance;

  }

  /**

  * 查询数据库

  */

  public function select($table,$condition=array(),$field = array()){

    $where='';

    if(!empty($condition)){

      foreach($condition as $k=>$v){

        $where.=$k."='".$v."' and ";

      }

      $where='where '.$where .'1=1';

    }

    $fieldstr = '';

    if(!empty($field)){

      foreach($field as $k=>$v){

        $fieldstr.= $v.',';

      }

      $fieldstr = rtrim($fieldstr,',');

    } else {

      $fieldstr = '*';

    }

    self::$sql = "select {$fieldstr} from {$table} {$where}";

    $result=mysql_query(self::$sql,$this->conn);

    $resuleRow = array();

    $i = 0;

    while($row=mysql_fetch_assoc($result)){

      foreach($row as $k=>$v){

        $resuleRow[$i][$k] = $v;

      }

    $i++;

    }

    return $resuleRow;

  }

  //添加一条记录

  public function insert($table,$data) {

    $values = '';

    $data = '';

    foreach ($data as $k=>$v) {

      $values .= $k.',';

      $datas .= "'$v'".',';

    }

    $values = rtrim($values,',');

    $datas = rtrim($datas,',');

    self::$sql = "INSERT INTO {$table} ({$values}) VALUES ({$datas})";

    if(mysql_query(self::$sql)) {

      return mysql_insert_id();

    } else {

      return false;

    }

  }

  //修改一条记录

  public function update($table,$data,$condition=array()){

    $where='';

    if(!empty($condition)) {

    foreach($condition as $k=>$v) {

      $where.=$k."='".$v."' and ";

    }

      $where='where '.$where .'1=1';

    }

    $updatastr = '';

    if(!empty($data)) {

    foreach($data as $k=>$v) {

      $updatastr.= $k."='".$v."',";

    }

      $updatastr = 'set '.rtrim($updatastr,',');

    }

    self::$sql = "update {$table} {$updatastr} {$where}";

    return mysql_query(self::$sql);

  }

  //删除记录

  public function delete($table,$condition) {

    $where='';

    if(!empty($condition)) {

      foreach($condition as $k=>$v) {

        $where.=$k."='".$v."' and ";

      }

      $where='where '.$where .'1=1';

    }

    self::$sql = "delete from {$table} {$where}";

    return mysql_query(self::$sql);

  }

  public static function getLastSql() {

    echo self::$sql;

  }

}

$db = db::getInstance();

//$list = $db->select('demo',array('name'=>'tom','password'=>'ds'),array('name','password'));

//echo $db->insert('demo',array('name'=>'最近你啦','password'=>'123'));

//echo $db->update('demo',array("name"=>'xxx',"password"=>'123'),array('id'=>1));

echo $db->delete('demo',array('id'=>'2'));

db::getLastSql();

echo "<pre>";

?>







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