门面模式加载数据库，按需加载，易于扩展。

静态调用Db类

use startmvc\core\Db;// 引入Db 类

$result = DB::table('article')->get();
dump($result);

表Table/From

table()和from()方法通用

### 用法1: 字符串参数
DB::table('table');
# 输出: "SELECT * FROM table"

DB::table('table1, table2');
# 输出: "SELECT * FROM table1, table2"

DB::table('table1 AS t1, table2 AS t2');
# 输出: "SELECT * FROM table1 AS t1, table2 AS t2"

### 用法2: 数组参数
DB::table(['table1', 'table2']);
# 输出: "SELECT * FROM table1, table2"

DB::table(['table1 AS t1', 'table2 AS t2']);
# 输出: "SELECT * FROM table1 AS t1, table2 AS t2"

以上的table可以用from代替