PHP 数据库连接工具类（MySQLI函数包装）

<?php

class mysql
{
    private $mysqli;
    private $result;

    /**
     * 数据库连接
     * @param $config 配置数组
     */
    public function connect($config)
    {
        $host = $config[‘host‘];        //主机地址
        $username = $config[‘username‘];//用户名
        $password = $config[‘password‘];//密码
        $database = $config[‘database‘];//数据库
        $port = $config[‘port‘];        //端口号

        $this->mysqli = new mysqli($host, $username, $password, $database, $port);
    }

    /**
     * 数据查询
     * @param $table 数据表
     * @param null $field 字段
     * @param null $where 条件
     * @return mixed 查询结果数目
     */
    public function select($table, $field = null, $where = null)
    {
        $sql = "SELECT * FROM {$table}";
        if (!empty($field)) {
            $field = ‘`‘ . implode(‘`,`‘, $field) . ‘`‘;
            $sql = str_replace(‘*‘, $field, $sql);
        }
        if (!empty($where)) {
            $sql = $sql . ‘ WHERE ‘ . $where;
        }
        $this->result = $this->mysqli->query($sql);
        return $this->result->num_rows;
    }

    /**
     * @return mixed 获取全部结果
     */
    public function fetchAll()
    {
        return $this->result->fetch_all(MYSQLI_ASSOC);
    }

    /**
     * 插入数据
     * @param $table 数据表
     * @param $data 数据数组
     * @return mixed 插入ID
     */
    public function insert($table, $data)
    {
        foreach ($data as $key => $value) {
            $data[$key] = $this->mysqli->real_escape_string($value);
        }
        $keys = ‘`‘ . implode(‘`,`‘, array_keys($data)) . ‘`‘;
        $values = ‘\‘‘ . implode("‘,‘", array_values($data)) . ‘\‘‘;
        $sql = "INSERT INTO {$table}( {$keys} )VALUES( {$values} )";
        $this->mysqli->query($sql);
        return $this->mysqli->insert_id;
    }

    /**
     * 更新数据
     * @param $table 数据表
     * @param $data 数据数组
     * @param $where 过滤条件
     * @return mixed 受影响记录
     */
    public function update($table, $data, $where)
    {
        foreach ($data as $key => $value) {
            $data[$key] = $this->mysqli->real_escape_string($value);
        }
        $sets = array();
        foreach ($data as $key => $value) {
            $kstr = ‘`‘ . $key . ‘`‘;
            $vstr = ‘\‘‘ . $value . ‘\‘‘;
            array_push($sets, $kstr . ‘=‘ . $vstr);
        }
        $kav = implode(‘,‘, $sets);
        $sql = "UPDATE {$table} SET {$kav} WHERE {$where}";
        $this->mysqli->query($sql);
        return $this->mysqli->affected_rows;
    }

    /**
     * 删除数据
     * @param $table 数据表
     * @param $where 过滤条件
     * @return mixed 受影响记录
     */
    public function delete($table, $where)
    {
        $sql = "DELETE FROM {$table} WHERE {$where}";
        $this->mysqli->query($sql);
        return $this->mysqli->affected_rows;
    }
}