Back end database paging is implemented according to limit
The first writing method: limit the number of pages offset start position
select id,name,sex,tel,addr from user limit 1 offset 1;
select * from student limit pageSize offset (pageNumber-1)*pageSize
The second writing method: limit starting position, number of pages
select id,name from user limit 1,2;
select * from studnet limit (pageNumber-1)*pageSize,pageSize
When the data volume is large, sub query is used for paging
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, 1) limit the number of pages;
Pagination of background data in Python code
views.py file
The Page() function is a method of the inner class of mypage.py
User? Count() is the method to get the total number of mysql data
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.py
class Page(): def __init__(self, page_num, total_count, url_prefix, per_page, max_page=4): """ :param page_num: Current page number :param total_count: Total data :param url_prefix: a Label href Prefix :param per_page: How many pieces of data are displayed per page :param max_page: Maximum number of pages displayed on the page """ self.url_prefix = url_prefix self.max_page = max_page #How many pieces of data are displayed on each page #How many pages are needed to show total_page, m = divmod(total_count, per_page) if m: total_page += 1 self.total_page = total_page try: page_num = int(page_num) #If the number of pages entered exceeds the maximum number of pages, the last page will be returned by default if page_num > total_page: page_num = total_page except Exception as e: #When the entered page number is not a positive number, the data of the first page will be returned by default page_num = 1 self.page_num = page_num #How many pages are displayed on the page if total_page < self.max_page: self.max_page = total_page @property def num(self): return self.page_num def page_html(self): #Make your own HTML code html_str_list = [] #Add the first page html_str_list.append('<li><a href="{}?page=1">home page</a></li>'.format( self.url_prefix)) #Judge if it is the first page, there is no previous page if self.page_num <= 1: html_str_list.append('<li><a href="#"><span aria-hidden="true">«</span></a></li>'.format(self.page_num-1)) else: #Add a label from the previous page 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): #Add an active style class to the current page if i == self.page_num: tmp = '<li><a href="?page="></a></li>'.format(self.url_prefix, i) else: tmp = '<li><a href="?page="></a></li>'.format( self.url_prefix, i) html_str_list.append(tmp) #Add a button for the next page #Judge, if it is the last page, there is no next page if self.page_num >= self.total_page: html_str_list.append('<li><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)) #Add last page html_str_list.append('<li><a href="{}?page={}">Tail page</a></li>'.format( self.url_prefix, self.total_page)) page_html = "".join(html_str_list) return page_html
models,py
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': 'male' if line[2] else 'female', 'age': line[3], 'tel': line[4], 'addr': line[5], 'role': line[6] } ) cursor.close() conn.close() return users