conn = sqlite3.connect(db_file)
    cursor = conn.cursor()
    cursor.execute('select * from user')
    values = cursor.fetchall()
    cursor.close()
    conn.close()
    name = []
    def by_score(t):
        for i in t:
            if isinstance(i,int):
                return(i)
    L = sorted(values, key=by_score)
    for i in range(len(L)):
        if isinstance(i,int) and low <= L[i][2] <= high:
            name.append(L[i][1])
    return name