db.php

<?php

class DB{
    private static $dbcon = false;
    private $host;
    private $port;
    private $username;
    private $password;
    private $db;
    private $charset;
    private $link;

    //私有构造方法
    private function __construct(){
        $this->host = '192.168.10.10';
        $this->port = '3306';
        $this->username = 'homestead';
        $this->password = 'secret';
        $this->db = 'queue';
        $this->charset = 'utf8';
        
        //链接数据库
        $this->db_connect();

        //选择数据库
        $this->db_usedb();

        //设置字符集
        $this->db_charset();
    }

    private function db_connect(){
        $this->link = mysqli_connect($this->host.':'.$this->port,$this->username,$this->password);
        if(!$this->link){
            echo '数据库连接失败!</br>';
            echo '错误编码：'.mysqli_errno($this->link).'</br>';
            echo '错误信息：'.mysqli_error($this->link).'</br>';
            exit();
        }
    }

    //设置字符集
    private function db_charset(){
        mysqli_query($this->link,"set names {$this->charset}");
    }

    //选择数据库
    private function db_usedb(){
        mysqli_query($this->link,"use {$this->db}");
    }

    //私有克隆，禁止克隆实现单例
    private function __clone(){
        die('clone is not allowed');
    }

    //公共的静态方法
    public static function getIntance(){
        if(self::$dbcon==false){
            self::$dbcon = new self;
        }
        return self::$dbcon;
    }

    //执行sql语句的方法
    public function query($sql){
        $res = mysqli_query($this->link,$sql);
        if(!$res){
            echo 'sql语句执行失败!</br>';
            echo '错误编码：'.mysqli_errno($this->link).'</br>';
            echo '错误信息：'.mysqli_error($this->link).'</br>';
            exit();            
        }
        return $res;
    }

    //获得最后一条记录id
    public function getInsertid(){
        return mysqli_insert_id($this->link);
    }

    //查询某个字段
    public function getOne(){
        $query = $this->query($sql);
        return mysqli_free_result($query); //释放结果集内存
    }

    public function getRow($sql,$type='assoc'){
        $query = $this->query($sql);
        if(!in_array($type,array('assoc','array','row'))){
            die('mysql_query error');
        }
        $funcname = "mysql_fetch_".$type;
        return $funcname($query);
    }

    //获取一条记录,前置条件通过资源获取一条记录
    public function getFormSource($query,$type="assoc"){
    if(!in_array($type,array("assoc","array","row")))
    {
      die("mysqli_query error");
    }
    $funcname="mysqli_fetch_".$type;
    return $funcname($query);
    }

    //获取多条数据，二维数组
    public function getAll($sql){
     $query=$this->query($sql);
     $list=array();
     while ($r=$this->getFormSource($query)) {
      $list[]=$r;
     }
     return $list;
    }

    public function selectAll($table,$where,$fields='*',$order='',$skip=0,$limit=1000){
        if(is_array($where)){
            foreach($where as $key=>$val){
                if(is_numeric($val)){
                    $condition = $key.'='.$val;
                }else{
                    $condition = $key.'=\"'.$val.'\"';
                }
            }
        }else{
            $condition = $where;
        }
        if(!empty($order)){
            $order = " order by ".$order;
        }
        $sql = "select $fields from $table where $condition $order limit $skip,$limit";
        $query = $this->query($sql);
        $list = array();
        while($r=$this->getFormSource($query)){
            $list[] = $r;
        }
        return $list;
    }

    //定义添加数据的方法
    public function insert($table,$data){
        //遍历数组得到每个字段和字段的值
        $key_str='';
        $v_str='';
        foreach($data as $key=>$v){
            //$key的值是每个字段s一个字段所对应的值
            $key_str.=$key.',';
            $v_str.="'$v',";
        }
        $key_str = trim($key_str,',');
        $v_str = trim($v_str,',');
        //判断数据是否为空
        $sql = "insert into $table ($key_str) values ($v_str)";
        $this->query($sql);
        //返回上一次增加操作产生的ID值
        return $this->getInsertid();
    }

    //删除一条数据
    public function deleteOne($table,$where){
        if(is_array($where)){
            foreach($where as $key=>$val){
                $condition = $key.'='.$val;
            }
        }else{
            $condition = $where;
        }
        $sql = "delete from $table where $condition";
        $this->query($sql);
        //返回受影响的行数
        return mysqli_affected_rows($this->link);
    }

    //删除多条数据
    public function deleteAll($table,$where){
        if(is_array($where)){
            foreach($where as $key=>$val){
                if(is_array($val)){
                    $condition = $key.' in ('.implode(',',$val).')';
                }else{
                    $condition = $key. '=' .$val;
                }
            }
        }else{
            $condition = $where;
        }
        $sql = "delete from $table where $condition";
        $this->query($sql);
        //返回受影响的行数
        return mysqli_affected_rows($this->link);        
    }

    //修改操作description
    public function update($table,$data,$where,$limit=0){
        //遍历数组，得到每一个字段和字段的值
        $str = '';
        foreach($data as $key=>$v){
            $str.="$key='$v',";
        }
        $str = rtrim($str,',');
        if(is_array($where)){
            foreach($where as $key=>$val){
                if(is_array($val)){
                    $condition = $key.' in ('.implode(',',$val) .')';
                }else{
                    $condition = $key. '=' .$val;
                }
            }
        }else{
            $condition = $where;
        }
        if(!empty($limit)){
            $limit = " limit ".$limit;
        }else{
            $limit='';
        }
        //修改sql语句
        $sql = "update $table set $str where $condition $limit";
        $this->query($sql);
        //返回受影响的行数
        return mysqli_affected_rows($this->link);
    }



}