sql-statement-load-data: add DuplicateOpt (#21806)

[ti-chi-bot]

This is an automated cherry-pick of #21806

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Copy DuplicateOpt from sql-statements/sql-statement-create-table.md

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[gemini-code-assist]

Summary of Changes

Hello @ti-chi-bot, 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 enhances the documentation for LOAD DATA SQL statements by explicitly defining and explaining the DuplicateOpt clause. This update provides users with clear guidance on how to handle duplicate data during data loading operations, offering options to either replace existing records or ignore duplicates, thereby improving data import control and predictability.

Highlights

• Documenting DuplicateOpt for LOAD DATA: This pull request introduces comprehensive documentation for the DuplicateOpt clause within LOAD DATA SQL statements, clarifying how users can manage duplicate data during bulk imports.
• Grammar Definition Update: The grammar definition for LOAD DATA in sql-statements/sql-statement-load-data.md has been updated to formally include the DuplicateOpt syntax, allowing for IGNORE or REPLACE keywords.
• Explanation of REPLACE and IGNORE Behavior: A new section has been added to detail the functionality of REPLACE (overwrites existing data) and IGNORE (skips duplicate rows) options, along with the default error behavior for duplicate data.

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[gemini-code-assist]

Code Review

This pull request adds documentation for the REPLACE and IGNORE options in the LOAD DATA statement. The changes are generally good, but I've suggested a couple of minor improvements for clarity and style consistency. Specifically, I've pointed out a trailing whitespace and recommended more precise descriptions for the REPLACE and IGNORE options to better explain their behavior with duplicate key values.

[hfxsd]

/approve

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hfxsd

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