PHP 数据库连接工具类（MySQLI函数包装）

====================mysql=====================

<?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;
    }
}

====================使用方法=====================

<?php
require_once 'mysql.class.php';

/* 配置连接参数 */
$config = array(
    'type' => 'mysql',
    'host' => 'localhost',
    'username' => 'woider',
    'password' => '3243',
    'database' => 'php',
    'port' => '3306'
);

/* 连接数据库 */
$mysql = new mysql();
$mysql->connect($config);


/* 查询数据 */

//1、查询所有数据
$table = 'mysqli';//数据表
$num = $mysql->select($table);
echo '共查询到' . $num . '条数据';
print_r($mysql->fetchAll());

//2、查询部分数据
$field = array('username', 'password'); //过滤字段
$where = 'id % 2 =0';                   //过滤条件
$mysql->select($table, $field, $where);
print_r($mysql->fetchAll());


/* 插入数据 */
$table = 'mysqli';//数据表
$data = array(    //数据数组
    'username' => 'admin',
    'password' => sha1('admin')
);
$id = $mysql->insert($table, $data);
echo '插入记录的ID为' . $id;

/* 修改数据 */
$table = 'mysqli';//数据表
$data = array(
    'password' => sha1('nimda')
);
$where = 'id = 44';
$rows = $mysql->update($table, $data, $where);
echo '受影响的记录数量为' . $rows . '条';

/* 删除数据 */
$table = 'mysqli';
$where = 'id = 45';
$rows = $mysql->delete($table, $where);
echo '已删除' . $rows . '条数据';