orm_sqlalchemy/sqlalchemy_20/db.py

from sqlalchemy import create_engine, text, insert, update, select, delete, engine_from_config
from sqlalchemy.orm import Session, sessionmaker
import configparser
import sys

sys.path.append(r'..')
from sqlalchemy_14.db_schema import User, Student

# 创建引擎
HOST = "home.rogersun.cn"
USER = "root"
PWD = "Sxzgx1209"
PORT = "3306"
DB = "orm_sqlalchemy"

URI = f"mysql+pymysql://{USER}:{PWD}@{HOST}:{PORT}/{DB}?charset=utf8"

engine = create_engine(
    URI,
    echo=True,  # echo = 'debug'
    future=True,  # 使用2.0接口
    pool_size=5,  # 连接池设置，0表示无限制
    max_overflow=0,  # 设置溢出
    pool_timeout=30,  #
    pool_recycle=3600,  # 设置时间以限制多久自动断开
    pool_logging_name='test_pool',  #
    pool_pre_ping=True,
    isolation_level="AUTOCOMMIT",
    query_cache_size=200,
)

# 从配置文件获取数据库链接
# config = configparser.ConfigParser()
# config.read_file(open('config.ini', 'r'))
# print(config.items('db_source'))
# engine = engine_from_config(dict(config.items('db_source')), pool_size=1, max_overflow=0, pool_timeout=0.1)

# 执行纯sql
# 无参数
# stmt = text("SELECT * FROM user")
# with engine.connect() as conn:
#     result = conn.execute(stmt).all()
#     print(result)

# 有参数
# with engine.connect() as conn:
#     stmt = text("INSERT INTO user (name, password) VALUES (:name, :password)")
#     params = [{'name': 'test1', 'password': 'test1pwd'}, {'name': 'test2', 'password': 'test2pwd'}]
#     result = conn.execute(stmt, params)
#     print(result)
#     conn.commit()

# 绑定参数  todo 不成功
# with engine.connect() as conn:
#     stmt = text("INSERT INTO user (name, password) VALUES (:name, :password)").bindparams(
#         {'name': 'test3', 'password': 'test3pwd'})
#     result = conn.execute(stmt)
#     print(result)
#     conn.commit()

# 获取结果
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}")
    # 列指定的名称
    # for row in result:
    #     name, password = row.name, row.password
    #     print(f"name: {name}, password: {password}")
    # 绑定模型
    # result: [User] = result.fetchall()
    # for row in result:
    #     name = row.name
    #     password = row.password
    #     print(f"name: {name}, password: {password}")

# 创建Session实例
# with Session(engine) as session:
#     stmt = text("SELECT * FROM user")
#     result = session.execute(stmt)
#     for row in result:
#         print(f"name: {row.name} - password: {row.password}")

# 2.0 增删改查
db_session = sessionmaker(bind=engine)()
# insert 方式1
# insert_stmt = insert(User).values({'name': 'sql2_test1', 'password': 'pwd1'})
# with db_session as sess:
#     result = sess.execute(insert_stmt)
#     print(result)
#     sess.commit()

# insert 方式2
insert_stmt2 = insert(User)
insert_data2 = {'name': 'sql2_test2', 'password': 'pwd2'}
# with db_session as sess:
#     result = sess.execute(insert_stmt2, insert_data2)
#     print(result)
#     sess.commit()

# insert 批量插入
# insert_data3 = [{'name': 'sql2_test3', 'password': 'pwd3'}, {'name': 'sql2_test4', 'password': 'pwd4'}]
# with db_session as sess:
#     result = sess.execute(insert_stmt2, insert_data3)
#     sess.commit()

# insert begin方式
# insert_data4 = [{'name': 'sql2_test5', 'password': 'pwd5'}, {'name': 'sql2_test6', 'password': 'pwd6'}]
# with db_session.begin():
#     db_session.execute(insert_stmt2, insert_data4)
#     db_session.commit()
#
# insert 对像方式
# insert_obj1 = User(name='sql2_test7', password='pwd7')
# with db_session as sess:
#     sess.add(insert_obj1)
#     sess.commit()

# 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()

# 查
# get 通过id
# result = db_session.get(User, 4)
# print(result)

# select all scalars
# result = db_session.execute(select(User)).scalars().all()  # [<1 name:rogersun>, <2 name:honeyhoney>, <3 name:haha>]
# print(result)
# for row in result:
#     print(f"{row.name} - {row.password}")

# select all
# result = db_session.execute(select(User)).all()  # [(<1 name:rogersun>,), (<2 name:honeyhoney>,), (<3 name:haha>,)]
# print(result)
# for row in result:
#     print(f"{row[0].name} - {row[0].password}")

# select filter_by
# result = db_session.execute(select(User).filter_by(name='roger')).fetchone()
# print(result[0].name)

# select filter
# result = db_session.execute(select(User).where(User.id <= 4)).scalars().all()
# print(result)
# print(r[0][0].name)

# select from_statement
# result = db_session.execute(select(User).from_statement(text('SELECT * FROM user'))).scalars().all()
# for row in result:
#     print(row.name)

# 遍历数据

# 元组赋值 all
# result = db_session.execute(select(User.id, User.name, User.password).where(User.id <= 4)).all()
# print(result)
# for _id, name, password in result:
#     print(f"{_id} - {name} - {password}")

# # 索引 all
# result = db_session.execute(select(User).where(User.id <= 4)).all()
# print(result)
# for row in result:
#     _id, name, password = row[0].id, row[0].name, row[0].password
#     print(f"{_id} - {name} - {password}")

# # 属性 scalers
# result = db_session.execute(select(User).where(User.id <= 4)).scalars().all()
# print(result)
# for row in result:
#     _id, name, password = row.id, row.name, row.password
#     print(f"{_id} - {name} - {password}")

# # 映射
# result = db_session.execute(select(User.id, User.name, User.password).where(User.id <= 4))
# print(result)
# for dict_row in result.mappings():
#     _id, name, password = dict_row['id'], dict_row['name'], dict_row['password']
#     print(f"{_id} - {name} - {password}")

# update
# r = db_session.execute(update(User).filter_by(name='roger').values(password='rogerpwd123').execution_options(
#     synchronize_session='evaluate'))
# print(r)
# db_session.commit()
# synchronize_session 有三种选项： false, "fetch", "evaluate"，默认是 evaluate
# false 表示完全不更新 Python 中的对象
# fetch 表示重新从数据库中加载一份对象
# evaluate 表示在更新数据库的同时，也尽量在 Python 中的对象上使用同样的操作