Why does the MySQL database correspond to fields that have data but use MyBatis to take out is 0 or null

Because the corresponding fields in the database use underscores, such as the spec_name used in entity Specname,

The data can be extracted after the entity has been changed to Spec_name. The upper field in the database corresponds to the upper in the entity and is also

Can take out the data.

Summary: MyBatis can resolve the case inconsistency between the database field and the entity's attributes, but after the database field is underlined, the mybatis cannot tell that the field is recognized as a property

　　　　

Why does the MySQL database correspond to fields that have data but use MyBatis to take out is 0 or null