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Do not merge until v8.5.4: MySQL compatibility about decimal insert through jdbc #22007

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Nov 10, 2025
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Do not merge until v8.5.4: MySQL compatibility about decimal insert through jdbc #22007

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MySQL compatibility about decimal insert through jdbc
ChangRui-Ryan Nov 4, 2025
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hfxsd Nov 5, 2025
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11 changes: 11 additions & 0 deletions develop/dev-guide-sample-application-java-jdbc.md
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Expand Up @@ -310,6 +310,17 @@
- Reduce [boilerplate code](https://en.wikipedia.org/wiki/Boilerplate_code) for managing connections and transactions.
- Manipulate data with data objects instead of a number of SQL statements.

### MySQL compatibility

In MySQL, when you insert data into a `DECIMAL` column, if the number of decimal places exceeds the column's defined scale, MySQL automatically truncates the extra digits and inserts the truncated data successfully, regardless of how many extra decimal places there are.

Check warning on line 315 in develop/dev-guide-sample-application-java-jdbc.md

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GitHub Actions / vale 

[vale] reported by reviewdog 🐶
[PingCAP.Ambiguous] Consider using a clearer word than 'many' because it may cause confusion.

Raw Output:
{"message": "[PingCAP.Ambiguous] Consider using a clearer word than 'many' because it may cause confusion.", "location": {"path": "develop/dev-guide-sample-application-java-jdbc.md", "range": {"start": {"line": 315, "column": 235}}}, "severity": "INFO"}

In TiDB v8.5.3 and earlier versions:

- If the number of decimal places exceeds the defined scale but does not exceed 72, TiDB also automatically truncates the extra digits and inserts the truncated data successfully.
- However, if the number of decimal places exceeds 72, the insertion fails and returns an error.

Starting from TiDB v8.5.4, TiDB aligns its behavior with MySQL: regardless of how many extra decimal places there are, it automatically truncates the extra digits and inserts the truncated data successfully.

Check warning on line 322 in develop/dev-guide-sample-application-java-jdbc.md

View workflow job for this annotation

GitHub Actions / vale 

[vale] reported by reviewdog 🐶
[PingCAP.Ambiguous] Consider using a clearer word than 'many' because it may cause confusion.

Raw Output:
{"message": "[PingCAP.Ambiguous] Consider using a clearer word than 'many' because it may cause confusion.", "location": {"path": "develop/dev-guide-sample-application-java-jdbc.md", "range": {"start": {"line": 322, "column": 83}}}, "severity": "INFO"}

## Next steps

- Learn more usage of MySQL Connector/J from [the documentation of MySQL Connector/J](https://dev.mysql.com/doc/connector-j/en/).
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