How to handle a null return from selectOne in MyBatis?

In MyBatis, if selectOne returns null, there are usually a few ways to resolve this.

1. Check the SQL statement to ensure that the query is correct and that the data being returned actually exists in the database.
2. Check parameters: Ensure that the parameters passed in are correct and meet the search criteria, as incorrect parameters may result in a null query result.
3. Check mapping: Ensure that MyBatis mapping configuration is correct, where ResultMap or ResultType configurations correspond with the query results.
4. Handle the return results with Optional: After calling the selectOne method, you can use the Optional class to handle the return results and avoid NullPointerException.
5. Add a null check logic: After retrieving the result from selectOne, add a check for null. If the result is null, handle it accordingly.

By using the above methods, you can address the issue of MyBatis returning null in selectOne. If the problem still persists, you can debug and troubleshoot by using methods such as logging to identify the specific reasons.

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