11.Django database Operations (execute native SQL)

1. Using the Extra method

Explanation: A result set modifier, a mechanism that provides additional query parameters

Description: Dependent model models

When used in the Where:

Book.objects.filter (publisher_id= "1"). Extra (where=["title= ' python Learning 1 '"])

Used after select

Book.objects.filter (publisher_id= "1"). Extra (select={"Count": "SELECT COUNT (*) from Hello_book"})

2. Using the Raw method

Explanation: Executing the original SQL and returning the model

Description: Dependent model for querying

Usage:

Book = Book.objects.raw ("SELECT * from Hello_book")
For item in book:
Print (Item.title)

3. Execute custom SQL

Explanation: Using cursors to perform

Import: from django.db import connection

Description: Not dependent on model

Usage:

From django.db Import Connection

cursor = Connection.cursor ()
#插入
Cursor.execute ("INSERT into Hello_author (name) VALUES (' Xiaol ')")
#更新
Cursor.execute ("Update hello_author set name= ' Xiaol ' where id=1")
#删除
Cursor.execute ("Delete from Hello_author where name= ' Xiaol '")
#查询
Cursor.execute ("SELECT * from Hello_author")
#返回一行
Raw = Cursor.fetchone ()
Print (RAW)
# #返回所有
# Cursor.fetchall ()

11.Django database Operations (execute native SQL)