PHP单表操作mysqli数据库类的封装

class DB{
 private $options=array(
   'database_type' => 'mysql',
      'database_name' => 'test',
      'server' => 'localhost',
      'username' => 'root',
      'password' => '',
      'charset' => 'utf8'
 );
 private $link;
 static private $instance=null;
 static $table;
 private function __construct(){  
  $this->db_connect();
  $this->db_setcharset();
 }
 static public function getInstance($table){
  if(!$table) exit('请输入要操作的数据表名');
  self::$table=$table;
  if (!self::$instance instanceof self) {
               self::$instance = new self($config);
           }
          return self::$instance;
 }
 private function db_connect(){
  $options=$this->options;
      try {
           $this->link = new mysqli($options['server'], $options['username'], $options['password'],$options['database_name']);
       }
      catch (Exception $e) {
           die("数据库连接失败".$e);
      }
 }
 private function db_setcharset(){
  $options=$this->options;
  if (!$this->link->set_charset($options['charset'])) {
       printf("Error loading  : %s\n", $this->link->error);
  }
 }
 private function __clone(){
  die('禁止复制对象实例');
 }
 private function db_query($sql){
  $res=$this->link->query($sql);
  var_dump($sql);
  if(!$res) printf("命令错误: %s\n", $mysqli->error);
  return $res;
 }
 public function insert($data){
  $keys=join(",",array_keys($data));
  foreach ($data as $key => $value) {
   # code...
   $value=$this->link->escape_string($value);
  }
  $values="'".join("','",array_values($data))."'";
  $sql="INSERT INTO ".self::$table." ({$keys}) VALUES ({$values})";
  $res=$this->db_query($sql);
  return $this->link->affected_rows;
 }
 public function delete($where=null,$tag='and'){
  // $where=array("age<28")
  $condation=$this->dealWhere($where,$tag);
  $sql="delete from ".self::$table.($where==null?null:" where ". $condation);;
  $res=$this->db_query($sql);
  return $this->link->affected_rows;
 }
 private function dealWhere($where,$tag){
  if(is_array($where)&&count($where)>0){
   foreach ($where as $key => $value) {
    $condation.=' '.$value.' '.$tag;
   }
   $condation=trim($condation,$tag);
  }elseif(!empty($where)){
   $condation=$where;
  }else{
   $condation='';
  }
  return $condation;
 }
 public function update($data,$where=null,$tag='and'){
  // $where=array("age<28")
  $condation=$this->dealWhere($where,$tag);
  if(is_array($where)&&count($where)>0){
   foreach ($where as $key => $value) {
    $condation.=' '.$value.' '.$tag;
   }
   $condation=trim($condation,$tag);
  }elseif(!empty($where)){
   $condation=$where;
  }
  $values='';
  foreach ($data as $key => $value) {
   # code...
   echo $key;
   $value=$this->link->escape_string($value);
   $values.=$key."='".$value."',";
  }
  $values=trim($values,',');
  $sql="update  ".self::$table." set {$values}".($where==null?null:" where ". $condation);
  $res=$this->db_query($sql);
  return $this->link->affected_rows;
 }
 public function select($where=null,$filed='*',$tag='and',$order=null,$limit=null){
  $condation=$this->dealWhere($where,$tag);
  $sql="select  {$filed} from ".self::$table.($where==null?null:" where ". $condation).($order==null?null:" order by ". $order).($limit==null?null:" limit ". $limit);
  $res=$this->db_query($sql);
  $rows=[];
   while ($row = $res->fetch_assoc()) {
           $rows[]=$row;
       }
  return $rows; 
 }

}
header('content-type:text/html;charset=utf-8');
$db=DB::getInstance('user');
//$insert_id=$db->update(array('username'=>'hello','age'=>30),'id=14');
$rows=$db->select('id>2','*','and',null,'4');
var_dump($rows);

转载于:https://www.cnblogs.com/zaoa/p/9418955.html