/**
 * @Author: 小破孩嫩
 * @Email: 3584685883@qq.com
 * @Time: 2020/12/23 16:08
 * @param int $column_num
 * @return mixed
 * @Description：获取表格列数的字母
 */
public function getMaxColumn(int $column_num)
{
    try{
        if(empty($column_num)){
            throw new Exception('column_num:列数为空~');
        }
        if(!is_int($column_num)){
            throw new Exception('column_num:参数类型错误~');
        }
        if($column_num > 26*26 || $column_num < 0){
            throw new Exception('最大列数：676列,最小列数：1列');
        }
        $column_word = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'];
        //生成循环次数
        $num = ceil($column_num/26);
        for($c = 0; $c < $num; $c++) {
            $first_word = $column_word[$c-1];
            foreach($column_word as $key => $val){
                if($c >= 1){
                    $word = $first_word.$column_word[$key];
                }else{
                    $word = $column_word[$key];
                }
                $column[] = $word;
            }
        }
        for($a = 0; $a < $column_num; $a++){
            $new_column[] = $column[$a];
        }
        return $new_column;
    }catch (Exception $e){
        returnResponse(100,$e->getMessage());
    }
}