Mysqli 数据库连接类

<?php
namespace Lib;

// 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 $link;
    //私有的构造方法
    private function __construct($config) {
        $this->host = $config['host'] ? $config['host'] : 'localhost';
        $this->port = $config['port'] ? $config['port'] : '3306';
        $this->user = $config['user'] ? $config['user'] : 'root';
        $this->pass = $config['pass'] ? $config['pass'] : '';
        $this->db = $config['db'] ? $config['db'] : '';
        $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($config = null) {
        if (self::$dbcon == false) {
            self::$dbcon = new self($config);
        }
        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);
    }
    /**
     * [获取字段可否为空]
     * @param  [string] $table [description]
     * @return [array]        [description]
     */
    public function getField_nullable($table) {
        $sql = "select COLUMN_NAME,IS_NULLABLE from information_schema.COLUMNS where table_name='$table'";
        $res = $this->getAll($sql);
        $arr = array();
        foreach ($res as $value) {
            if ($value['IS_NULLABLE'] == 'NO') {
                $arr[$value['COLUMN_NAME']] = false;
                continue;
            }
            $arr[$value['COLUMN_NAME']] = true;
        }
        return $arr;
    }
    /**
     * [获取字段数据类型]
     * @param  [string] $table [description]
     * @return [array]        [description]
     */
    public function getField_dataType($table) {
        $sql = "select COLUMN_NAME,DATA_TYPE from information_schema.COLUMNS where table_name='$table'";
        $res = $this->getAll($sql);
        $arr = array();
        foreach ($res as $value) {
            $arr[$value['COLUMN_NAME']] = $value['DATA_TYPE'];
        }
        return $arr;
    }
}