sql*net message from client

sql*net message from client是Oracle数据库中的一种网络通信协议，表示客户端向服务器发送了一个SQL语句或其他请求。这个消息通常是由Oracle数据库的监听程序接收并处理，然后将结果返回给客户端。在Oracle数据库中，sql*net message from client通常是一个非常常见的事件，因为它代表了数据库与客户端之间的通信。

相关问题

File "D:\pythonProject\venv\client.py", line 45, in add_Line cursor.execute(sql, (time, ip, content,)) File "src\pymssql\_pymssql.pyx", line 476, in pymssql._pymssql.Cursor.execute pymssql._pymssql.ProgrammingError: (102, b"Incorrect syntax near '?'.DB-Lib error message 20018, severity 15:\nGeneral SQL Server error: Check messages from the SQL Server\n")

这个错误可能是由于 SQL 语句中的某些字符没有被正确转义导致的。你可以尝试使用 `pymssql.escape()` 函数来转义特殊字符，例如：

sql = "INSERT INTO mytable (time, ip, content) VALUES (%s, %s, %s)"
sql = sql.encode('utf-8')
sql = pymssql.escape(sql).decode('utf-8')
cursor.execute(sql, (time, ip, content))

另外，你还需要确保 SQL 语句中的表名、列名等标识符用反引号（`）或方括号（[]）括起来，例如：

sql = "INSERT INTO `mytable` (`time`, `ip`, `content`) VALUES (%s, %s, %s)"

或者

sql = "INSERT INTO [mytable] ([time], [ip], [content]) VALUES (%s, %s, %s)"

这样可以避免 SQL 语句中的关键字和保留字与标识符冲突。

1. Draw a UML sequence diagram that models the following events in a three-tier database client-server architecture: The client applet sends a connection request to the database servlet, which sends back a password request. The user supplies a username and password, which are sent back to the database servlet. The username and password are correct, so the servlet responds with an "OK" message. The user enters search parameters in the applet interface, and the client applet translates these into an SQL query, which is sent to the database servlet. The database servlet sends the SQL query to the remote database, which sends back the results of the query. The servlet passes the results back to the client applet.

Sure, here is a UML sequence diagram that models the events you described:

Client Applet              Database Servlet             Remote Database
       |                             |                             |
       |----> Connection Request ---->|                             |
       |                             |<---- Password Request ------|
       |      Username & Password    |                             |
       |<---- Password Challenge -----|                             |
       |                             |----> Validation Request ---->|
       |                             |      Username & Password    |
       |                             |<----- Validation Result ----|
       |    Search Parameters & SQL  |                             |
       |----> SQL Query Request ---->|                             |
       |                             |----> SQL Query Request ---->|
       |                             |        SQL Query            |
       |                             |<----- Query Results --------|
       |<---- Query Results ---------|                             |

In this diagram, each horizontal line represents an object or component in the system, and the vertical arrows represent messages being passed between them. The arrows are labeled with the message name and any parameters being passed. The diagram shows the flow of events from the client applet's initial connection request through to the retrieval of query results.