How to Select Specific Columns (projectId and projectName) from a Database Using Spring JPA Projections?

How to Selectively Fetch Data From Database in Spring JPA

Spring JPA provides various ways to query data and retrieve specific columns from database tables. One effective method is to use projections, an essential technique in Spring Data JPA. Projections allow you to define the shape and content of the result returned from a query.

In your specific case, you seek to select only the projectId and projectName columns from the projects table. To achieve this using projections, you can create an interface with getters for the desired columns. In your scenario, you would define an interface called ProjectIdAndName:

interface ProjectIdAndName{
    String getId();
    String getName();
}

Once you have defined your projection interface, you need to add a method to your repository that returns the projection. In this case, you can add the following method to your repository:

List<ProjectIdAndName> findAll();

This method will return a list of ProjectIdAndName objects, each representing a row in the projects table, with only the projectId and projectName columns populated. By using this projection-based approach, you can efficiently retrieve only the specific data you require, optimizing your database queries.

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