PHP DB 数据库连接类封装（自己封装Db类-亲测可用）

<?php

namespace app\api\controller;

class Db{
    //私有的属性
    private static $dbcon=false;
    private $host;
    private $port;
    private $user;
    private $pass;
    private $db;
    private $charset;
    private $link;
    //私有的构造方法
    private function __construct(){
        $this->host =  '127.0.0.1';
        $this->port =  '3306';
        $this->user =  'milu';
        $this->pass =  'JxwXfDP5226hghhaRmRmzxxj1222hjhj';
        $this->db =  'milu';
        $this->charset= 'utf8';
        //连接数据库
        $this->db_connect();
        //选择数据库
        $this->db_usedb();
        //设置字符集
        $this->db_charset();
    }
    //连接数据库
    private function db_connect(){
        $this->link=mysqli_connect($this->host.':'.$this->port,$this->user,$this->pass);
        if(!$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}");
    }
    //私有的克隆
    private function __clone(){
        die('clone is not allowed');
    }
    //公用的静态方法
    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 "错误编码是".mysqli_errno($this->link)."<br>";
            echo "错误信息是".mysqli_error($this->link)."<br>";
        }
        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
     * @param
     * @return string or int
     */
    public function getOne($sql){
        $query=$this->query($sql);
        return mysqli_free_result($query);
    }
    //获取一行记录,return array 一维数组
    public function getRow($sql,$type="assoc"){
        $query=$this->query($sql);
        if(!in_array($type,array("assoc",'array',"row"))){
            die("mysqli_query error");
        }
        $funcname="mysqli_fetch_".$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;
    }


    // xm封装单个查询方法，支持输入表名和查询条件
    public function find($table, $where = [], $fields='*') {
        $sql = "SELECT $fields FROM $table";
        if (!empty($where)) {
            $sql .= " WHERE ";
            $firstCondition = true;
            foreach ($where as $key => $value) {
                if (!$firstCondition) {
                    $sql .= " AND ";
                }
                $sql .= "$key = :$key";
                $params[$key] = $value;
                $firstCondition = false;
            }
            $sql .= " ";
        }
        $query= $this->query($sql);
        $data=$this->getFormSource($query,'row');
        return $data;
    }

    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
     * @param string $table 表名
     * @param string orarray $data [数据]
     * @return int 最新添加的id
     */
    public function insert($table,$data){
        //遍历数组，得到每一个字段和字段的值
        $key_str='';
        $v_str='';
        foreach($data as $key=>$v){
            //  if(empty($v)){
            //   die("error");
            // }
            //$key的值是每一个字段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);
        //返回上一次增加操做产生ID值
        return $this->getInsertid();
    }
    /*
     * 删除一条数据方法
     * @param1 $table, $where=array('id'=>'1') 表名 条件
     * @return 受影响的行数
     */
    public function delete($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);
    }
    /*
    * 删除多条数据方法
    * @param1 $table, $where 表名 条件
    * @return 受影响的行数
    */
    public function deleteAll($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]
     * @param [type] $table [表名]
     * @param [type] $data [数据]
     * @param [type] $where [条件]
     * @return [type]
     */
    public function update($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);
    }
}

$db = DB::getIntance();
$insert_data = ['order_id'=>'10010','order_amount' = '200.00','status'=> 1];
$res = $db->insert('order_info',$insert_data);