Sqlite 当我尝试检索已排序的行时，DB返回空列表

我对烧瓶不熟悉。我正在尝试根据表单中选定的选项对数据库中的行进行排序。问题是，我得到的是空列表，而不是包含行数据的元组列表。虽然post请求和my DB都不是空的，而且我的SQL请求正在sqlitebrowser中与我的当前DB一起工作

routes.py：

@bp.route('/poll-process', methods=['POST', 'GET'])
def process():
    form =  ChoiceForm(request.form)
    if request.method == 'POST':
        select = request.form.get('sel')  
        if select:
            print(select)
            db = get_db()
            res = db.execute(
            '''SELECT username, sex, city, emotion, month, poll_time
                FROM poll
                JOIN author
                    ON poll.author_id = author.id
                ORDER BY sex ASC''', (select)                  
            ).fetchall()
            print(res) 
            db.close
    return render_template('process.html', form=form)

shema.sql：

DROP TABLE IF EXISTS author;
DROP TABLE IF EXISTS poll;

CREATE TABLE `author` (
    `id`    INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
    `username`  TEXT NOT NULL,
    `sex`   TEXT NOT NULL
);

CREATE TABLE `poll` (
    `poll_id`   INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
    `city`  TEXT NOT NULL,
    `emotion`   TEXT NOT NULL,
    `month` TEXT NOT NULL,
    `poll_time` TEXT NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `author_id`   INTEGER,   
  FOREIGN KEY(`author_id`) REFERENCES `author`
);

process.html：

<form method="post">
  <!-- select -->
  <div class="form-group mt-4">  
    <h2>Choose criteria to sort</h2>
    <select class="custom-select" name="sel">        
      {% for field in form.sel %}
        <option>{{ field }}</option>    
      {% endfor %}      
    </select>
    ...
    {{form.submit(class="btn btn-primary")}}
</form>

提前谢谢

在routes.py中更改查询

@bp.route'/poll process'，methods=['POST'，'GET'] def流程： form=ChoiceFormrequest.form 如果request.method==“POST”： select=request.form.get'sel' 如果选择： 打印选择 db=get_db res=db.execute '选择用户名、性别、城市、情感、月份、投票时间 民意测验 加入作者 ON poll.author\u id=author.id 订单由%s“%s”选择， .fetchall 印刷品 db.close 返回render_模板'process.html'，form=form

 * Serving Flask app "flaskapp" (lazy loading)
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poll_time
[]
127.0.0.1 - - [30/Oct/2019 21:16:59] "POST /poll-process HTTP/1.1" 200 -