9.30 博客项目迭代1.3

2018-9-30 18:45:02

 

迭代了自己博客项目

放上github : https://github.com/TrueNewBee/bbs_demo

明天周一 十一  已经没啥概念啦!对放假

明天继续迭代自己的博客项目!! 然后把Django复习一下 整理一下笔记!

博客项目还是蛮成功的,就是就有点丑!可以优化!!!

每次一的优化,都是值得期待的!

越努力,越幸运!永远不要高估自己!

 

ORM分组实例

import os


if __name__ == '__main__':
    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "orm_demo.settings")
    import django
    django.setup()

    from app01 import models
    # ORM分组查询 每个部门名称及部门的平均工资

    # ret = models.Employee.objects.all()
    # """
    # SELECT `employee`.`id`, `employee`.`name`, `employee`.`age`, `employee`.`salary`, `employee`.`province`, `employee`.`dept` FROM `employee` LIMIT 21; args=()
    # """
    # print(ret)

    # ret = models.Employee.objects.all().values("dept", "age")
    # """
    # SELECT `employee`.`dept`, `employee`.`age` FROM `employee` LIMIT 21; args=()
    # """
    # print(ret)

    from django.db.models import Avg
    # ret = models.Employee.objects.values("province").annotate(a=Avg("salary")).values("province", "a")
    # """
    # SELECT `employee`.`province`, AVG(`employee`.`salary`) AS `a` FROM `employee` GROUP BY `employee`.`province` ORDER BY NULL LIMIT 21; args=()
    # """
    # print(ret)

    # ORM连表分组查询
    # ret = models.Person.objects.values("dept_id").annotate(a=Avg("salary")).values("dept__name", "a")
    # """
    # SELECT `dept`.`name`, AVG(`person`.`salary`) AS `a` FROM `person` INNER JOIN `dept` ON (`person`.`dept_id` = `dept`.`id`) GROUP BY `person`.`dept_id`, `dept`.`name` ORDER BY NULL LIMIT 21; args=()
    # """
    # print(ret)

    # 查询person表，判断每个人的工资是否大于2000
    # ret = models.Person.objects.all().extra(
    #     select={"gt": "salary > 2000"}
    # )
    #
    # """
    # SELECT (salary > 2000) AS `gt`, `person`.`id`, `person`.`name`, `person`.`salary`, `person`.`dept_id` FROM `person` LIMIT 21; args=()
    # """
    # # print(ret)
    # for i in ret:
    #     print(i.name, i.gt)


    # 执行原生的SQL语句
    from django.db import connection
    cursor = connection.cursor()  # 获取光标，等待执行SQL语句
    cursor.execute("""SELECT * from person where id = %s""", [1])
    row = cursor.fetchone()
    print(row)

 

日期归档查询和部分其他查询示例

import os


if __name__ == '__main__':
    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "bbs.settings")

    import django
    django.setup()

    from blog import models


    # 查询a1对应的评论数
    # ret = models.Article.objects.first().comment_set.all()
    # print(ret)

    # 查询某个分类对应的文章
    from django.db.models import Count
    user = models.UserInfo.objects.filter(username="xiaohei").first()
    blog = user.blog
    # ret = models.Category.objects.filter(blog=blog)  # 求小黑站点下面所有的文章分类
    # ret = ret[0].article_set.all()  # 技术分类下面所有的文章
    # for i in ret:
    #     print(i.title, i.article_set.all().count())

    # ret = models.Category.objects.filter(blog=blog).annotate(c=Count("article")).values("title", "c")
    # print(ret)
    # 基于QuerySet查询的时候 不用加set
    # models.Category.objects.filter(blog=blog).values("article__title")

    ret = models.Article.objects.filter(user=user).extra(
        select={"archive_ym": "date_format(create_time,'%%Y-%%m')"}
    ).values("archive_ym").annotate(c=Count("nid")).values("archive_ym", "c")
    print(ret)

 

笔记

day78 2018-05-25

1. 复习下分组和聚合  https://www.cnblogs.com/liwenzhou/p/8660826.html

    1. 分组
        ORM中values或者values_list 里面写什么字段，就相当于select 什么字段
        
        ret = models.Employee.objects.all().values("dept", "age")
        相当于：
        SELECT `employee`.`dept`, `employee`.`age` FROM `employee` LIMIT 21; args=()
        
    2. ORM中 annotate 前面是什么就按照什么分组！
        from django.db.models import Avg
        ret = models.Employee.objects.values("province").annotate(a=Avg("salary")).values("province", "a")
        相当于：
        SELECT `employee`.`province`, AVG(`employee`.`salary`) AS `a` FROM `employee` GROUP BY `employee`.`province` ORDER BY NULL LIMIT 21; args=()

    3. extra  --> 在执行ORM查询的时候执行额外的SQL语句
        # 查询person表，判断每个人的工资是否大于2000
        ret = models.Person.objects.all().extra(
            select={"gt": "salary > 2000"}
        )
        相当于：
        SELECT (salary > 2000) AS `gt`, `person`.`id`, `person`.`name`, `person`.`salary`, `person`.`dept_id` FROM `person` LIMIT 21; args=()


    4. 直接执行原生的SQL语句，类似pymysql的用法
        from django.db import connection
        cursor = connection.cursor()  # 获取光标，等待执行SQL语句
        cursor.execute("""SELECT * from person where id = %s""", [1])
        row = cursor.fetchone()
        print(row)
        


2. 个人站点首页
    - 分组和聚合查询
        1. 文章分类
        2. 标签分类
    
        3. 日期归档
            1. MySQL内置的方法：date_format(字段名, "%Y-%m")  
            2. extra() --> 执行额外的原生SQL语句
                ret = models.Article.objects.filter(user=user).extra(
                    select={"archive_ym": "date_format(create_time,'%%Y-%%m')"}
                ).values("archive_ym").annotate(c=Count("nid")).values("archive_ym", "c")