2.0学习进度 80%

sqlalchemy_20/db.py

@@ -1,4 +1,4 @@
-from sqlalchemy import create_engine, text, insert, update, select, delete, engine_from_config
+from sqlalchemy import create_engine, text, insert, update, select, delete, engine_from_config, or_, and_, func
 from sqlalchemy.orm import Session, sessionmaker
 import configparser
 import sys
@@ -13,7 +13,7 @@ PWD = "Sxzgx1209"
 PORT = "3306"
 DB = "orm_sqlalchemy"
 
-URI = f"mysql+pymysql://{USER}:{PWD}@{HOST}:{PORT}/{DB}?charset=utf8"
+URI = f"mysql+pymysql://{USER}:{PWD}@{HOST}:{PORT}/{DB}?charset=utf8mb4"
 
 engine = create_engine(
     URI,
@@ -59,9 +59,9 @@ engine = create_engine(
 #     conn.commit()
 
 # 获取结果
-stmt = text("SELECT * FROM user")
-with engine.connect() as conn:
-    result = conn.execute(stmt)
+# stmt = text("SELECT * FROM user")
+# with engine.connect() as conn:
+#     result = conn.execute(stmt)
 # 解包赋值
 # for _id, name, password in result:
 #     print(f"name: {name}, password: {password}")
@@ -120,17 +120,145 @@ insert_data2 = {'name': 'sql2_test2', 'password': 'pwd2'}
 
 # insert 对象方式 批量
 # insert_obj2 = User(name='sql2_test8', password='pwd8')
-# insert_obj3 = User(name='sql2_test9', password='pwd9')
 # with db_session as sess:
 #     # sess.bulk_save_objects([insert_obj2, insert_obj3])
 #     sess.add_all([insert_obj2, insert_obj3])
 #     sess.commit()
 
+# add
+# with db_session as sess:
+#     user_obj = User(name='add', password='addpwd123')
+#     sess.add(user_obj)
+#     sess.flush()  # 刷新数据库表
+#     print(user_obj.id)  # 获取数据对应id
+#     sess.commit()
+
 # 查
+
 # get 通过id
 # result = db_session.get(User, 4)
 # print(result)
 
+# sqlalchemy1.4: session.query(User).all()
+# query_cursor = db_session.execute(select(User))
+# print(query_cursor.all())  # 数据指针，当all取过数据后one将得到None
+# print(query_cursor.first())
+# for row in query_cursor.scalars():
+#     print(row)  # row.name格式可以取到数据
+
+# sqlalchemy1.4: session.query(User).filter_by(name='roger').all()
+# sql_stmt = select(User).filter_by(name='roger')
+# query_result = db_session.execute(sql_stmt).one()
+# print(query_result)
+# print(query_result[0].name)
+
+# sqlalchemy1.4: session.query(User).filter(User.id == 2).all()
+# sql_stmt = select(User).where(User.id == 2)
+# query_result = db_session.execute(sql_stmt).scalars()
+# for row in query_result:
+#     print(f"{row.id} - {row.name} - {row.password}")
+
+# sqlalchemy1.4: session.query(User).filter(User.id >= 2).first()
+# sql_stmt = select(User).where(User.id >= 2)
+# query_result = db_session.execute(sql_stmt).scalars()
+# for row in query_result:
+#     print(f"{row.id} - {row.name} - {row.password}")
+
+# sqlalchemy1.4: session.query(User).filter(User.id >= 2).order_by(User.id.desc()).all()
+# sql_stmt = select(User).where(User.id >= 2).order_by(User.id.desc())
+# query_result = db_session.execute(sql_stmt).scalars()
+# for row in query_result:
+#     print(f"{row.id} - {row.name} - {row.password}")
+
+# sqlalchemy1.4: session.query(User).filter(User.id >= 2).filter(User.name.like('%one%')).all()
+# sql_stmt = select(User).where(User.id >= 2).where(User.name.like('%one%'))
+# query_result = db_session.execute(sql_stmt).scalars()
+# for row in query_result:
+#     print(f"{row.id} - {row.name} - {row.password}")
+
+# sqlalchemy1.4: session.query(User).filter(User.id.in_([1, 2, 3])).all()
+# sql_stmt = select(User).where(User.id.in_([1, 2, 3]))
+# query_result = db_session.execute(sql_stmt).scalars()
+# for row in query_result:
+#     print(f"{row.id} - {row.name} - {row.password}")
+
+# sqlalchemy1.4: session.query(User).filter(User.id.in_(session.query(User.id).filter(User.name.startswith('he')))).all()
+# 连写
+# sql_stmt = select(User).where(User.id.in_(
+#     db_session.execute(select(User.id).where(User.name.startswith('he'))).scalars()))
+# query_result = db_session.execute(sql_stmt).scalars()
+# for row in query_result:
+#     print(f"{row.id} - {row.name} - {row.password}")
+# 拆分
+# sql_stmt1 = select(User.id).where(User.name.startswith('he'))
+# query_result1 = db_session.execute(sql_stmt1).scalars()
+# sql_stmt2 = select(User).where(User.id.in_(query_result1))
+# query_result2 = db_session.execute(sql_stmt2).scalars()
+# for row in query_result2:
+#     print(f"{row.id} - {row.name} - {row.password}")
+
+# sqlalchemy1.4: session.query(User).filter(User.id.notin_([1, 2])).all()
+# sql_stmt = select(User).where(User.id.notin_([1, 2]))
+# query_result = db_session.execute(sql_stmt).scalars()
+# for row in query_result:
+#     print(f"{row.id} - {row.name} - {row.password}")
+
+# sqlalchemy1.4: session.query(User).filter(User.password is None).all()
+# sqlalchemy1.4: session.query(User).filter(User.password.is_(None)).all()
+# sql_stmt = select(User).where(User.password.is_(None))  # 此处不支持 is None
+# query_result = db_session.execute(sql_stmt).scalars()
+# for row in query_result:
+#     print(f"{row.id} - {row.name} - {row.password}")
+
+# sqlalchemy1.4: session.query(User).filter(User.password is not None).all()
+# sqlalchemy1.4: session.query(User).filter(User.password.isnot(None)).all()
+# sql_stmt = select(User).where(User.password.isnot(None))  # isnot()
+# sql_stmt = select(User).where(User.password.is_not(None))  # is_not()
+# query_result = db_session.execute(sql_stmt).scalars()
+# for row in query_result:
+#     print(f"{row.id} - {row.name} - {row.password}")
+
+# sqlalchemy1.4: session.query(User).filter(or_(User.id > 2, User.name.ilike('Rog%'))).all()
+# sql_stmt = select(User).where(or_(User.id > 2, User.name.ilike('ROG%')))
+# query_result = db_session.execute(sql_stmt).scalars()
+# for row in query_result:
+#     print(f"{row.id} - {row.name} - {row.password}")
+
+# sqlalchemy1.4: session.query(User).filter(and_(User.id >= 2, User.name.endswith('ei')))
+# sql_stmt = select(User).where(and_(User.id >= 2, User.name.endswith('ei')))
+# query_result = db_session.execute(sql_stmt).scalars()
+# for row in query_result:
+#     print(f"{row.id} - {row.name} - {row.password}")
+
+# sqlalchemy1.4: session.query(User.name.label('user_name'), User.password).filter(User.id >= 2).all()
+# sql_stmt = select(User.name.label('user_name_label'), User.password.label('user_pwd_label')).where(User.id >= 2)
+# query_result = db_session.execute(sql_stmt).all()  # 返回 [('honeyhoney', '2222'), ('haha', '123321'), ('hehe', '3333')]
+# query_result = db_session.execute(sql_stmt).scalars()  # 返回 scalars 对象， 仅包含name
+# query_result = db_session.execute(sql_stmt)  # 返回 {'user_name_label': 'roger', 'user_pwd_label': 'rogerpwd123'} 建议此情况
+# print(query_result)
+# for row in query_result:
+#     print(row)
+# for row in query_result.mappings():
+#     print(row['user_name_label'], row['user_pwd_label'])
+
+# sqlalchemy1.4: session.query(User).filter(User.id > 1).count()
+# sql_stmt = select(func.count()).select_from(User).where(User.id <= 2)
+# query_result = db_session.execute(sql_stmt).scalar()
+# print(query_result)
+
+
+# try:
+#     result = session.query(User).filter(User.id > 1).one()  # one 当仅查询到一个结果时返回，否则抛出异常
+# except Exception as e:
+#     print(e)
+# result = session.query(User).filter(User.id == 1).one_or_none()  # one_or_none 当查询结果仅一条时显示返回结果，当没有结果时返回None，否则抛出异常
+# result = session.query(User).filter(User.id == 1).scalar()  # 调用one方法，并在成功时返回行的第一列
+# result = session.query(User).filter(User.id > 1).group_by(User.password)
+# result = session.query(func.max(User.id)).all()  # func.max
+# print(result[0].name, result[0].password)
+# print(result)  # 定义 __repr__ 后可以打印
+
+
 # select all scalars
 # result = db_session.execute(select(User)).scalars().all()  # [<1 name:rogersun>, <2 name:honeyhoney>, <3 name:haha>]
 # print(result)

sqlalchemy_20/db_obj.py

@@ -27,7 +27,8 @@ class Student(Base):
         return f"<{self.id}-{self.name}-{self.gender}-{self.date}>"
 
 
-Base.metadata.create_all(engine)
+Base.metadata.create_all(engine)  # 创建全部表
+User.__table__.create(engine)  # 创建单个表
 
 # 创建表结构 -- 命令式