Merge pull request #1107 from yangj1211/sqlqlchemy

update use sqlalchemy connect mo

docs/MatrixOne/Develop/connect-mo/python-connect-to-matrixone.md

@@ -93,37 +93,45 @@ SQLAlchemy 是 Python SQL 工具包和对象关系映射器 (ORM)，它为应用
     ```sql
     mysql> create database test;
     mysql> use test;
-    mysql> create table student (name varchar(20), age int);
-    mysql> insert into student values ("tom", 11), ("alice", "10");
-
+    mysql> create table student (id int primary key,name varchar(20), age int);
+    mysql> insert into student values (1,"tom", 11), (2,"alice", "10");
     ```
 
 3. 创建一个纯文本文件 *sqlalchemy_connect_matrixone.py* 并将代码写入文件：
 
     ```python
-    #!/usr/bin/python3
-    from sqlalchemy import create_engine, text
-
-    # Open database connection
-    my_conn = create_engine("mysql+mysqldb://root:[email protected]:6001/test")
-
-    # execute SQL query using execute() method.
-    query=text("SELECT * FROM student LIMIT 0,10")
-    my_data=my_conn.execute(query)
-
-    # print SQL result
-    for row in my_data:
-            print("name:", row["name"])
-            print("age:", row["age"])
-
+    from sqlalchemy import create_engine
+    from sqlalchemy.orm import declarative_base as _declarative_base
+    from sqlalchemy import Column, Integer, String
+    from sqlalchemy.orm import sessionmaker
+
+    #使用 SQLAlchemy 创建到 MatrixOne 的连接字符串，并创建一个引擎（Engine）
+    connection_string = 'mysql+pymysql://root:[email protected]:6001/test'
+    engine = create_engine(connection_string)
+
+    Base = _declarative_base()
+
+    #定义一个 Python 类来映射 student 表。
+    class Student(Base):
+        __tablename__ = 'student'
+        id = Column(Integer, primary_key=True)
+        name = Column(String)
+        age = Column(Integer)
+
+    #使用 sessionmaker 创建一个会话来执行查询
+    Session = sessionmaker(bind=engine)
+    session = Session()
+
+    #使用 SQLAlchemy 的查询接口来查询 student 表中的数据。
+    users = session.query(Student).all()
+    for user in users:
+        print(f'ID: {user.id}, Name: {user.name}, Age: {user.age}')
     ```
 
 4. 打开一个终端，在终端内执行下面的命令：
 
     ```
     python3 sqlalchemy_connect_matrixone.py
-    name: tom
-    age: 11
-    name: alice
-    age: 10
+    ID: 1, Name: tom, Age: 11
+    ID: 2, Name: alice, Age: 10
     ```