Django执行原生SQL的三种方法 򚛞

Posted 2022-08-02 gqy02

原文: http://blog.gqylpy.com/gqy/383

"> 如下三种方式

1. extra：结果集修改器，一种提供额外查询参数的机制
2. raw：执行原始SQL返回模型实例
3. connection/connections：直接执行自定义SQL（此方法不依赖model）

1.extra示例：

# extra
# 在QuerySet的基础上继续执行子语句
# extra(self, select=None, where=None, params=None, tables=None, order_by=None, select_params=None)

# select和select_params是一组，where和params是一组，tables用来设置from哪个表
# 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'])

举个例子：
models.UserInfo.objects.extra(
                    select='newid':'select count(1) from test01_usertype where id>%s',
                    select_params=[1,],
                    where = ['age>%s'],
                    params=[18,],
                    order_by=['-age'],
                    tables=['test01_usertype']
                )
"""相当于：
select 
    test01_userinfo.id,
    (select count(1) from test01_usertype where id>1) as newid
from test01_userinfo,test01_usertype
where 
    test01_userinfo.age > 18
order by 
    test01_userinfo.age desc
"""

2.raw示例

models.UserInfo.objects.raw('select * from test01_UserInfo')

3.直接执行自定义SQL

# 执行原生SQL
# 更高灵活度的方式执行原生SQL语句

from django.db import connection, connections
cursor = connection.cursor()
# cursor = connections['default'].cursor()

cursor.execute("""SELECT * from auth_user where id = %s""", [1])

# 插入数据
cursor.execute("insert into table(field) value('xx')")

# 更新数据
cursor.execure("update table set name='xx' where name='xxx'")

# 删除数据
cursor.execure("delete from table where name='xx'")

# 查询操作
cursor.execute("select * from table")


# -- 取查询结果（返回元组） --

# 返回结果行游标直读向前，读取一条
row = cursor.fetchone()

# 读取所有
cursor.fetchall()

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原文: http://blog.gqylpy.com/gqy/383