Using Spring boot JPA getting data from existing oracle db

Question

Hi I have an existing oracle db, which contains tables. Need to get data from multiple tables using jpa from spring boot api below are my questions

1. Do I need model classes of those multiple tables or I don't need model classes to get the required column data? 2.Can I write a custom query joining multiple tables and get the list of values from my db using jpa?

Answer 1

I presume you are trying to expose the query results as a spring boot rest API. You need to have some object definition to hold the query results into memory. It is always a good idea to have a model to represent your query results for better manageability and maintainability of code. Certainly, you can achieve it without creating any models by storing all the results into a Map.

If you don't use models then you will be missing key features of ORM tools.

Just to answer your questions -

1. Do I need model classes of those multiple tables or I don't need model classes to get the required column data?

   Answer: Not required but recommended to use model classes.

2. Can I write a custom query joining multiple tables and get the list of values from my db using jpa?

   Answer: You can write the native SQL query by joining multiple tables.

You can find more examples here