Fix MyBatis selectKey Not Working: Top Reasons

There could be several reasons for the invalidity of selectKey in MyBatis.

1. Some databases do not support selectKey, which means that tools like MySQL’s LAST_INSERT_ID() or Oracle’s sequence may not work properly for automatically retrieving primary keys.
2. There is an error in the selectKey configuration: make sure that the correct properties like keyProperty and order are set when configuring selectKey, otherwise the generated primary key value cannot be obtained correctly.
3. SelectKey was not correctly utilized: When using selectKey, ensure to call selectKey before inserting data to obtain the generated primary key value, otherwise, you will not be able to retrieve the primary key value correctly.
4. Conflict in primary key generation strategies: Sometimes, different primary key generation strategies may result in selectKey being ineffective, such as having both automatic primary key generation and manually specifying a primary key configured at the same time, which can cause the selectKey to fail.
5. Database connection error: If there is an issue with the database connection, it may prevent the selectKey from executing properly, resulting in the inability to retrieve the generated primary key value.