後端數據庫分頁是根據limit實現的html
第一種寫法: limit 每頁的個數 offset 起始位置python
select id,name,sex,tel,addr from user limit 1 offset 1;
select * from student limit pageSize offset (pageNumber-1)*pageSize
第二種寫法: limit 起始位置,每頁的個數mysql
select id,name from user limit 1,2;
select * from studnet limit (pageNumber-1)*pageSize,pageSize
當數據量比較大的時候分頁採用子查詢的方式sql
select id,name from user where id >= (select id from user order by id limit 1,1) limit 2;
select id,name from user where id >= (select id from user order by id limit 起始位置,1) limit 每頁的個數;
Python代碼中實現後臺數據分頁
數據庫
views.py文件
後端
Page()函數是mypage.py裏邊類的方法session
user_count() 是獲取mysql 數據總數的方法app
def index(request): page_num = request.GET.get("page") login_user = request.session.get('user') count = user_count() per_page = 2 page_obj = Page(page_num, count,url_prefix="/users/",per_page=2, max_page=4,) page_num = page_obj.num users = mysql_page(per_page,page_num) page_html = page_obj.page_html() return render(request,'static/index.html',{"users": users,"login_user": login_user,"page_html": page_html})
mypage.pyide
class Page(): def __init__(self, page_num, total_count, url_prefix, per_page, max_page=4): """ :param page_num: 當前頁碼數 :param total_count: 數據總數 :param url_prefix: a標籤href的前綴 :param per_page: 每頁顯示多少條數據 :param max_page: 頁面上最多顯示幾個頁碼 """ self.url_prefix = url_prefix self.max_page = max_page # 每一頁顯示多少條數據 # 總共須要多少頁碼來展現 total_page, m = divmod(total_count, per_page) if m: total_page += 1 self.total_page = total_page try: page_num = int(page_num) # 若是輸入的頁碼數超過了最大的頁碼數,默認返回最後一頁 if page_num > total_page: page_num = total_page except Exception as e: # 當輸入的頁碼不是正經數字的時候 默認返回第一頁的數據 page_num = 1 self.page_num = page_num # 頁面上總共展現多少頁碼 if total_page < self.max_page: self.max_page = total_page @property def num(self): return self.page_num def page_html(self): # 本身拼接分頁的HTML代碼 html_str_list = [] # 加上第一頁 html_str_list.append('<li><a href="{}?page=1">首頁</a></li>'.format( self.url_prefix)) # 判斷一下 若是是第一頁,就沒有上一頁 if self.page_num <= 1: html_str_list.append('<li class="disabled"><a href="#"><span aria-hidden="true">«</span></a></li>'.format(self.page_num-1)) else: # 加一個上一頁的標籤 html_str_list.append('<li><a href="{}?page={}"><span aria-hidden="true">«</span></a></li>'.format( self.url_prefix, self.page_num-1)) for i in range(1,self.total_page+1): # 若是是當前頁就加一個active樣式類 if i == self.page_num: tmp = '<li class="active"><a href="{0}?page={1}">{1}</a></li>'.format(self.url_prefix, i) else: tmp = '<li><a href="{0}?page={1}">{1}</a></li>'.format( self.url_prefix, i) html_str_list.append(tmp) # 加一個下一頁的按鈕 # 判斷,若是是最後一頁,就沒有下一頁 if self.page_num >= self.total_page: html_str_list.append('<li class="disabled"><a href="#"><span aria-hidden="true">»</span></a></li>') else: html_str_list.append('<li><a href="{}?page={}"><span aria-hidden="true">»</span></a></li>'.format( self.url_prefix, self.page_num+1)) # 加最後一頁 html_str_list.append('<li><a href="{}?page={}">尾頁</a></li>'.format( self.url_prefix, self.total_page)) page_html = "".join(html_str_list) return page_html
models,py 函數
def mysql_page(per_page,page): start = (page - 1 ) * per_page sql = 'select id,name,sex,age,tel,addr,role from user where id >= \ ( select id from user order by id limit %s,1)limit %s' args = (start,per_page) conn = MySQLdb.connect(host=MYSQL_HOST, port=MYSQL_PORT, user=MYSQL_USER, passwd=MYSQL_PASSWORD, db=MYSQL_DB, charset='utf8mb4') cursor = conn.cursor() cursor.execute(sql, args) lines = cursor.fetchall() users = [] for line in lines: users.append({ 'id': line[0], 'name': line[1], 'sex': '男' if line[2] else '女', 'age': line[3], 'tel': line[4], 'addr': line[5], 'role': line[6] } ) cursor.close() conn.close() return users