The key to dealing with API authentication is to understand and use the authentication method correctly. 1. APIKey is the simplest authentication method, usually placed in the request header or URL parameters; 2. BasicAuth uses username and password for Base64 encoding transmission, which is suitable for internal systems; 3. OAuth2 needs to obtain the token first through client_id and client_secret, and then bring the BearerToken in the request header; 4. In order to deal with the token expiration, the token management class can be encapsulated and automatically refreshed the token; in short, selecting the appropriate method according to the document and safely storing the key information is the key.

In Python, variables defined inside a function are local variables and are only valid within the function; externally defined are global variables that can be read anywhere. 1. Local variables are destroyed as the function is executed; 2. The function can access global variables but cannot be modified directly, so the global keyword is required; 3. If you want to modify outer function variables in nested functions, you need to use the nonlocal keyword; 4. Variables with the same name do not affect each other in different scopes; 5. Global must be declared when modifying global variables, otherwise UnboundLocalError error will be raised. Understanding these rules helps avoid bugs and write more reliable functions.

To create modern and efficient APIs using Python, FastAPI is recommended; it is based on standard Python type prompts and can automatically generate documents, with excellent performance. After installing FastAPI and ASGI server uvicorn, you can write interface code. By defining routes, writing processing functions, and returning data, APIs can be quickly built. FastAPI supports a variety of HTTP methods and provides automatically generated SwaggerUI and ReDoc documentation systems. URL parameters can be captured through path definition, while query parameters can be implemented by setting default values ??for function parameters. The rational use of Pydantic models can help improve development efficiency and accuracy.

To test the API, you need to use Python's Requests library. The steps are to install the library, send requests, verify responses, set timeouts and retry. First, install the library through pipinstallrequests; then use requests.get() or requests.post() and other methods to send GET or POST requests; then check response.status_code and response.json() to ensure that the return result is in compliance with expectations; finally, add timeout parameters to set the timeout time, and combine the retrying library to achieve automatic retry to enhance stability.

The security of remote access to MySQL can be guaranteed by restricting permissions, encrypting communications, and regular audits. 1. Set a strong password and enable SSL encryption. Force-ssl-mode=REQUIRED when connecting to the client; 2. Restrict access to IP and user rights, create a dedicated account and grant the minimum necessary permissions, and disable root remote login; 3. Configure firewall rules, close unnecessary ports, and use springboard machines or SSH tunnels to enhance access control; 4. Enable logging and regularly audit connection behavior, use monitoring tools to detect abnormal activities in a timely manner to ensure database security.

CTEs are a feature introduced by MySQL8.0 to improve the readability and maintenance of complex queries. 1. CTE is a temporary result set, which is only valid in the current query, has a clear structure, and supports duplicate references; 2. Compared with subqueries, CTE is more readable, reusable and supports recursion; 3. Recursive CTE can process hierarchical data, such as organizational structure, which needs to include initial query and recursion parts; 4. Use suggestions include avoiding abuse, naming specifications, paying attention to performance and debugging methods.

MySQL's RecursiveCTE is mainly used to process hierarchical data. 1. It realizes traversal of the tree structure through initial queries and recursive queries, such as finding all subordinates of a certain employee; 2. It can be used to generate numerical sequences, such as 1 to 100; 3. When using them, you need to pay attention to avoid infinite loops, control recursive depth, optimize indexes, and first test small data to verify the correctness of the logic.

In Python, the method of traversing tuples with for loops includes directly iterating over elements, getting indexes and elements at the same time, and processing nested tuples. 1. Use the for loop directly to access each element in sequence without managing the index; 2. Use enumerate() to get the index and value at the same time. The default index is 0, and the start parameter can also be specified; 3. Nested tuples can be unpacked in the loop, but it is necessary to ensure that the subtuple structure is consistent, otherwise an unpacking error will be raised; in addition, the tuple is immutable and the content cannot be modified in the loop. Unwanted values can be ignored by \_. It is recommended to check whether the tuple is empty before traversing to avoid errors.