Because it is necessary to meet the needs of Java objects to be persisted (that is, saved).
ORM:(Object/Relation Mapping): Object/Relational Mapping
The realization idea of ORM:
Map the records in the table in the relational database into objects and display them in the form of objects. Programmers can convert operations on the database into operations on objects .
Therefore, the purpose of ORM is to facilitate developers to implement database operations with object-oriented ideas.
Refer to the following two figures for specific reference:
