要在 Python 中使用 MySQL 数据库进行增删改查（CRUD）操作，你可以使用 `pymysql` 库。以下是一些示例代码，展示如何实现这些操作。

首先，确保你已经安装了 `pymysql`。如果没有安装，可以通过以下命令安装：

```bash
pip install pymysql
```

### 1. 连接数据库

```python
import pymysql

# 连接数据库
conn = pymysql.connect(host='localhost', user='your_username', password='your_password', db='your_db', charset='utf8mb4')
```

### 2. 创建（Create）

```python
# 创建游标对象
cursor = conn.cursor()

# 插入数据
sql = "INSERT INTO patient (name, age, time) VALUES (%s, %s, %s)"
try:
    cursor.execute(sql, ('John Doe', 30, '2024-07-27 10:00:00'))
    conn.commit()  # 提交事务
except pymysql.Error as e:
    print(e)
    conn.rollback()  # 回滚事务

# 关闭游标和连接
cursor.close()
conn.close()
```

### 3. 读取（Read）

```python
# 创建游标对象
cursor = conn.cursor(pymysql.cursors.DictCursor)

# 查询所有数据
sql = "SELECT * FROM patient"
try:
    cursor.execute(sql)
    results = cursor.fetchall()
    for row in results:
        print(row)
except pymysql.Error as e:
    print(e)

# 关闭游标和连接
cursor.close()
conn.close()
```

### 4. 更新（Update）

```python
# 创建游标对象
cursor = conn.cursor()

# 更新数据
sql = "UPDATE patient SET age = %s WHERE name = %s"
try:
    cursor.execute(sql, (31, 'John Doe'))
    conn.commit()  # 提交事务
except pymysql.Error as e:
    print(e)
    conn.rollback()  # 回滚事务

# 关闭游标和连接
cursor.close()
conn.close()
```

### 5. 删除（Delete）

```python
# 创建游标对象
cursor = conn.cursor()

# 删除数据
sql = "DELETE FROM patient WHERE name = %s"
try:
    cursor.execute(sql, ('John Doe',))
    conn.commit()  # 提交事务
except pymysql.Error as e:
    print(e)
    conn.rollback()  # 回滚事务

# 关闭游标和连接
cursor.close()
conn.close()
```

### 完整示例

```python
import pymysql

# 连接数据库
conn = pymysql.connect(host='localhost', user='your_username', password='your_password', db='your_db', charset='utf8mb4')

# 创建游标对象
cursor = conn.cursor()

# 插入数据
sql_insert = "INSERT INTO patient (name, age, time) VALUES (%s, %s, %s)"
try:
    cursor.execute(sql_insert, ('John Doe', 30, '2024-07-27 10:00:00'))
    conn.commit()
except pymysql.Error as e:
    print(e)
    conn.rollback()

# 查询数据
sql_select = "SELECT * FROM patient"
try:
    cursor.execute(sql_select)
    results = cursor.fetchall()
    for row in results:
        print(row)
except pymysql.Error as e:
    print(e)

# 更新数据
sql_update = "UPDATE patient SET age = %s WHERE name = %s"
try:
    cursor.execute(sql_update, (31, 'John Doe'))
    conn.commit()
except pymysql.Error as e:
    print(e)
    conn.rollback()

# 删除数据
sql_delete = "DELETE FROM patient WHERE name = %s"
try:
    cursor.execute(sql_delete, ('John Doe',))
    conn.commit()
except pymysql.Error as e:
    print(e)
    conn.rollback()

# 关闭游标和连接
cursor.close()
conn.close()
```

确保替换 `your_username`, `your_password`, `your_db` 为你的 MySQL 数据库的实际用户名、密码和数据库名。同时，确保你的数据库服务器正在运行，并且你有足够的权限执行这些操作。