高级版查询操作,厉害了哦
#老规矩
from my_create_table import User,engine
from sqlalchemy.orm import sessionmaker
Session = sessionmaker(engine)
db_session = Session()
查询数据表操作
and or
from sqlalchemy.sql import and_ , or_
ret = db_session.query(User).filter(and_(User.id > 3, User.name == ‘DragonFire’)).all()
ret = db_session.query(User).filter(or_(User.id < 2, User.name == ‘DragonFire’)).all()
查询所有数据
r1 = db_session.query(User).all()
查询数据 指定查询数据列 加入别名
r2 = db_session.query(User.name.label(‘username’), User.id).first()
print(r2.id,r2.username) # 15 NBDragon
表达式筛选条件
r3 = db_session.query(User).filter(User.name == “DragonFire”).all()
原生SQL筛选条件
r4 = db_session.query(User).filter_by(name=‘DragonFire’).all()
r5 = db_session.query(User).filter_by(name=‘DragonFire’).first()
字符串匹配方式筛选条件 并使用 order_by进行排序
r6 = db_session.query(User).filter(text(“id<:value and name=:name”)).params(value=224, name=‘DragonFire’).order_by(User.id).all()
#原生SQL查询
r7 = db_session.query(User).from_statement(text(“SELECT * FROM User where name=:name”)).params(name=‘DragonFire’).all()
筛选查询列
query的时候我们不在使用User ORM对象,而是使用User.name来对内容进行选取
user_list = db_session.query(User.name).all()
print(user_list)
for row in user_list:
print(row.name)
别名映射 name as nick
user_list = db_session.query(User.name.label(“nick”)).all()
print(user_list)
for row in user_list:
print(row.nick) # 这里要写别名了
筛选条件格式
user_list = db_session.query(User).filter(User.name == “DragonFire”).all()
user_list = db_session.query(User).filter(User.name == “DragonFire”).first()
user_list = db_session.query(User).filter_by(name=“DragonFire”).first()
for row in user_list:
print(row.nick)
复杂查询
from sqlalchemy.sql import text
user_list = db_session.query(User).filter(text(“id<:value and name=:name”)).params(value=3,name=“DragonFire”)
查询语句
from sqlalchemy.sql import text
user_list = db_session.query(User).filter(text(“select * from User id<:value and name=:name”)).params(value=3,name=“DragonFire”)
排序 :
user_list = db_session.query(User).order_by(User.id).all()
user_list = db_session.query(User).order_by(User.id.desc()).all()
for row in user_list:
print(row.name,row.id)
#其他查询条件
“”"
ret = session.query(User).filter_by(name=‘DragonFire’).all()
ret = session.query(User).filter(User.id > 1, User.name == ‘DragonFire’).all()
ret = session.query(User).filter(User.id.between(1, 3), User.name == ‘DragonFire’).all() # between 大于1小于3的
ret = session.query(User).filter(User.id.in_([1,3,4])).all() # in_([1,3,4]) 只查询id等于1,3,4的
ret = session.query(User).filter(~User.id.in_([1,3,4])).all() # ~xxxx.in_([1,3,4]) 查询不等于1,3,4的
ret = session.query(User).filter(User.id.in_(session.query(User.id).filter_by(name=‘DragonFire’))).all() 子查询
from sqlalchemy import and_, or_
ret = session.query(User).filter(and_(User.id > 3, User.name == ‘DragonFire’)).all()
ret = session.query(User).filter(or_(User.id < 2, User.name == ‘DragonFire’)).all()
ret = session.query(User).filter(
or_(
User.id < 2,
and_(User.name == ‘eric’, User.id > 3),
User.extra != “”
)).all()
select * from User where id<2 or (name=“eric” and id>3) or extra != “”
通配符
ret = db_session.query(User).filter(User.name.like(‘e%’)).all()
ret = db_session.query(User).filter(~User.name.like(‘e%’)).all()
限制
ret = db_session.query(User)[1:2]
排序
ret = db_session.query(User).order_by(User.name.desc()).all()
ret = db_session.query(User).order_by(User.name.desc(), User.id.asc()).all()
分组
from sqlalchemy.sql import func
ret = db_session.query(User).group_by(User.extra).all()
ret = db_session.query(
func.max(User.id),
func.sum(User.id),
func.min(User.id)).group_by(User.name).all()
ret = db_session.query(
func.max(User.id),
func.sum(User.id),
func.min(User.id)).group_by(User.name).having(func.min(User.id) >2).all()
“”"
关闭连接
db_session.close()
orm_select_more
复制代码
更新：
复制代码
#高级版更新操作
from my_create_table import User,engine
from sqlalchemy.orm import sessionmaker
Session = sessionmaker(engine)
db_session = Session()
#直接修改
db_session.query(User).filter(User.id > 0).update({“name” : “099”})
#在原有值基础上添加 - 1
db_session.query(User).filter(User.id > 0).update({User.name: User.name + “099”}, synchronize_session=False)
#在原有值基础上添加 - 2
db_session.query(User).filter(User.id > 0).update({“age”: User.age + 1}, synchronize_session=“evaluate”)
db_session.commit()
orm_update_more
复制代码写自定义目录标题)
