[Fix] Fix DuckDB datasource creation from Web UI

[honglei]

Description

Fixes #3008

PR Description / PR 描述

Summary / 摘要

This PR fixes the issue where DuckDB datasources could not be correctly created or initialized from the Web UI. It ensures proper URI formatting and prevents schema-related SQL errors for DuckDB connections.

此 PR 修复了从 Web 界面创建或初始化 DuckDB 数据源失败的问题。主要通过修正 URI 格式化逻辑以及处理 DuckDB 在 SQL 执行中的 Schema 兼容性来解决。

Problem / 问题描述

1. Incorrect URI Initialization: The DuckDbConnector was using a raw file path instead of a properly formatted DB URL when being created from parameters, leading to connection failures.

2. Schema Incompatibility: In RDBMSConnector, DuckDB was not treated as a "schema-less" database (like SQLite). Passing a database name as a schema triggered errors during certain SQL operations.

3. URI 初始化错误: DuckDbConnector 在从参数创建时直接使用了原始文件路径，而非格式化后的 DB URL，导致连接失败。

4. Schema 不兼容: 在 RDBMSConnector 中，DuckDB 未像 SQLite 一样被视为“无 Schema”数据库。在某些 SQL 操作中传递数据库名作为 Schema 会触发错误。

Solution / 解决方案

• Update URI Construction: Changed DuckDbConnector.from_parameters to use parameters.db_url() instead of parameters.path, ensuring the URI matches the required format for DuckDB.

• Adjust Schema Logic: Updated RDBMSConnector to set _schema to None for DuckDB (matching SQLite behavior) to prevent SQL execution errors related to database/schema scoping.

• 更新 URI 构建: 将 DuckDbConnector.from_parameters 更改为使用 parameters.db_url() 而非 parameters.path，确保生成的 URI 符合 DuckDB 的要求。

• 调整 Schema 逻辑: 在 RDBMSConnector 中，将 DuckDB 设置为与 SQLite 相同的处理逻辑（即 _schema 为 None），以避免与数据库/模式范围相关的 SQL 执行错误。

How Has This Been Tested?

The fix has been verified after adopting the changes from duckdb_engine PR #1393.

Test Environment:

• OS: Windows 11 x64
• Python: 3.13
• DuckDB: 1.5.1
• SQLAlchemy: 2.0.48

Manual Verification: Successfully created a DuckDB datasource via the Web UI and verified the connection and metadata retrieval.

该修复在采纳了 duckdb_engine PR #1393 的更改后进行了验证。

测试环境：

• 操作系统: Windows 11 x64
• Python 版本: 3.13
• DuckDB 版本: 1.5.1
• SQLAlchemy 版本: 2.0.48

手动验证: 通过 Web 界面成功创建 DuckDB 数据源，并验证了连接及元数据获取。

Snapshots:

N/A

Checklist:

• My code follows the style guidelines of this project
• I have already rebased the commits and make the commit message conform to the project standard.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• Any dependent changes have been merged and published in downstream modules

[Aries-ckt]

Thank you for your feedback! For version information, please see:- Latest stable version: v0.7.5 (2025-02-11)- View all releases: https://github.com/eosphoros-ai/DB-GPT/releasesWe recommend upgrading to the latest version to get the latest features and fixes.

[chenliang15405]

Thanks for your contribution, LGTM

[Aries-ckt]

LGTM