extra

    a. 公司级别，查看2017每个月成单量
        - 客户分配表
        - 状态=成单
        - 时间
        ```
        select id,name,ctime,strftime("%Y-%m",ctime) as ftime from tb;
        
        # select id,name,ctime,date_format(ctime,"%Y-%m") from tb;

        select strftime("%Y-%m",ctime) as ftime,count('id') as ct as ftime from tb where status=2 and strftime("%Y",ctime)=2017 group by ftime
        ```

        # 复杂SQL

                - extra
                    models.XX.objects.extra(select={'ftime': "strftime('%%Y-%%m',ctime)"})
                        select 
                            id,
                            name,
                            strftime('%Y-%m',ctime) as ftime
                        from 
                            tb 
                        
                    models.XX.objects.extra(select={'n1': "select count(1) from tb1",'id':'id','name':'name'})
                        select 
                            id,
                            name,
                            (select count(1) from tb1) as n1
                        from 
                            tb 
                    
                    models.XX.objects.extra(select={'n1': "select count(1) from tb1 where id>%s",'id':'id','name':'name'},select_params=(11,))
                    
                        select 
                            id,
                            name,
                            (select count(1) from tb1 where id>11) as n1
                        from 
                            tb 
                            
                            
                    先进行字符串格式化，再执行SQL语句
                    
    ```             
                - 原生SQL

                 from django.db import connection, connections 
                 
                 
                 cursor = connections['default1'].cursor()
                 cursor = connection.cursor()
                 
                 cursor.execute("""SELECT * from auth_user where id = %s""", [1])
                 row = cursor.fetchone()
        
        # 实现：
            from django.db.models import Count
            models.CustomerDistribution.objects.filter(ctime__year=2017,status=2).extra(select={'mt':'strftime("%%Y-%%m",ctime)'}).values('mt').annotate(ct=Count('id'))

            # select strftime("%Y-%m",ctime) as ftime,count('id') as ct as ftime from tb where status=2 and strftime("%Y",ctime)=2017 group by ftime

        b. 公司级别，查看2017每个月成单比
        
            v1 = models.CustomerDistribution.objects.filter(ctime__year=2017, status=2).extra(
                select={'mt': 'strftime("%%Y-%%m",ctime)'}).values('mt').annotate(ct=Count('id'))
    
            v2 = models.CustomerDistribution.objects.filter(ctime__year=2017).extra(
                select={'mt': 'strftime("%%Y-%%m",ctime)'}).values('mt').annotate(ct=Count('id'))
    
    
        c. 查看员工的销售记录
            all_list = models.CustomerDistribution.objects.filter(ctime__gte=start_date,ctime__lte=end_date,status=2).values('user_id','ctime')
#补充

    # extra
    #
    # extra(self, select=None, where=None, params=None, tables=None, order_by=None, select_params=None)
    #    Entry.objects.extra(select={'new_id': "select col from sometable where othercol > %s"}, select_params=(1,))
    #    Entry.objects.extra(where=['headline=%s'], params=['Lennon'])
    #    Entry.objects.extra(where=["foo='a' OR bar = 'a'", "baz = 'a'"])
    #    Entry.objects.extra(select={'new_id': "select id from tb where id > %s"}, select_params=(1,), order_by=['-nid'])