fix: stmt2 query block

[Pengrongkun]

Description

https://project.feishu.cn/taosdata_td/defect/detail/6506118573

Issue(s)

• Close/close/Fix/fix/Resolve/resolve: Issue Link

Checklist

Please check the items in the checklist if applicable.

• Is the user manual updated?
• Are the test cases passed and automated?
• Is there no significant decrease in test coverage?

[gemini-code-assist]

Summary of Changes

Hello @Pengrongkun, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a bug in the stmt2 prepared statement mechanism, specifically when it interacts with information_schema.ins_tables queries that utilize placeholders. The core change involves improving the parser's ability to correctly interpret and bind values from placeholders for database and table names, ensuring accurate query execution. The changes are validated by a new dedicated test case.

Highlights

• Enhanced Placeholder Handling for Information Schema Queries: The parsing utility has been updated to correctly extract and process placeholder values (e.g., ?) when querying information_schema.ins_tables for db_name and table_name columns. This includes proper handling of NCHAR and VARCHAR data types and memory management for conversions.
• New Test Case for stmt2 Information Schema Queries: A new test case has been added to stmt2Test.cpp to validate the functionality of querying information_schema.ins_tables using prepared statements (stmt2) with bound parameters, ensuring the fix works as expected.
• Logging Level Adjustments: Several logging statements in clientStmt2.c have been adjusted, primarily changing ILOG_E to DLOG_E and TLOG to DLOG, to refine the verbosity of the client-side statement logging.

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[gemini-code-assist]

Code Review

This pull request appears to fix an issue with prepared statement queries, particularly for information_schema tables, by enhancing how placeholder values are handled in the parser. The changes in parUtil.c seem robust and correctly manage different data types and memory for placeholders. The logging levels in clientStmt2.c have been adjusted, which is a reasonable change. However, I've identified a couple of issues in the new test case in stmt2Test.cpp that should be addressed.

[gemini-code-assist]

This commented-out code should be removed to keep the codebase clean and maintainable.

[gemini-code-assist]

The assertion ASSERT_EQ(fieldNum, 2) is confusing. The function taos_stmt2_get_fields is expected to return the number of result columns, which is 3 for the query select table_name, db_name, stable_name .... The number of parameters for this query is 2.

If taos_stmt2_get_fields is intended to get the parameter count for SELECT queries, its name is misleading. If it's meant to get result fields, the assertion is incorrect. Please clarify the function's behavior for SELECT statements or correct the test. If you intended to get the number of parameters, a function like taos_stmt2_get_param_num should be used if available.