Django Query Database Common statements __ Database

Reference: Click to open link

1. Group BY & Order BY & Q

Aggregation + ordering, the corresponding SQL statement is:

Select Currentpid, COUNT (*) from stats_x

where type=3 and (status =1 or Status=0)

GROUP BY Currentpid

ORDER BY currentpid Desc

The corresponding Django notation:

Stats_x.objects.filter (q (type=3) & (Q (status=1) | Q (status=0)). VALUES (' Currentpid '). Annotate (Delta_count=count (' id ')). Order_by ('-currentpid ')

#order by-number is inverted.

#在annotate前面添加values, which is the column with the list of attributes as group by

#annotate, like aggregate, can be used for aggregation, but the column name after aggregate aggregation is fixed and cannot be customized, annotate can customize column names, such as Delta_count

Note: Q expression can not be used between and, must be used &

2. To be Continued ...