新增以查询字符串$value开头的所有查询like_first，跟以$value结尾的所有查询两个模糊查询方法like_last。源码改动如下！
protected $exp = ['<>' => 'ne', '=' => '=', '>' => 'gt', '>=' => 'gte', '<' => 'lt', '<=' => 'lte', 'in' => 'in', 'not in' => 'nin', 'nin' => 'nin', 'mod' => 'mod', 'exists' => 'exists', 'regex' => 'regex', 'type' => 'type', 'all' => 'all', '> time' => '> time', '< time' => '< time', 'between time' => 'between time', 'not between time' => 'not between time', 'notbetween time' => 'not between time', 'like' => 'like','like_first'=>'like_first','like_last'=>'like_last'];} elseif ('like' == $exp) {
// 模糊查询 采用正则方式
$query[$key] = $value instanceof Regex ? $value : new Regex("$value", 'i');
}elseif ('like_first' == $exp) {
// 模糊查询 采用正则方式查询以$value开头的所有数据
$query[$key] = $value instanceof Regex ? $value : new Regex("^$value", 'i');
}elseif ('like_last' == $exp) {
// 模糊查询 采用正则方式查询以$value结尾的所有数据
$query[$key] = $value instanceof Regex ? $value : new Regex("$value$", 'i');
}使用方法跟like一样。如下：where(['like',$value]); /*全局模糊查询*/
where(['like_first',$value]); /*以$value开头的所有数据*/
where(['like_last',$value]); /*以$value结尾的所有数据*/ 