PHP DB 数据库连接类定义与用法示例

<?php
// 数据库连接类
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 = 'localhost';
$this- port = '3306';
$this- user = 'root';
$this- pass = 'root';
$this- db = 'imooc';
$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 $list;
}
public function selectAll($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, $where=array('id'= '1') 表名 条件
* @return 受影响的行数
*/
public function deleteOne($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);