Planned lessonMID-022-L02

jOOQ in practice

Lesson 2 of 5
Mid-level

On This Lesson 4 topics

In this lesson
Planned topics
Draft outline details
Practice

This lesson is planned. The outline below lists the topics it will cover. The full lesson has not been published yet.

In this lesson

write type-safe SQL with generated classes.

Planned topics

jOOQ generates Java classes from the database schema (tables, columns, types) through a code generator in the build.
You write SQL as Java methods; the compiler catches renamed columns and wrong types.
It supports modern SQL (CTEs, window functions, ON CONFLICT) and maps results to records or DTOs.
Integrates with Spring transactions through DSLContext using the same DataSource.
Generate from a migrated database (Flyway plus Testcontainers) so the code and schema agree; verify licensing for your database edition before recording (open-source edition supports PostgreSQL).

Draft outline details

Demonstration

java

var rows = dsl.select(PRODUCT.CATEGORY_ID, DSL.sum(ORDER_ITEM.PRICE_CENTS))
              .from(ORDER_ITEM).join(PRODUCT).on(PRODUCT.ID.eq(ORDER_ITEM.PRODUCT_ID))
              .groupBy(PRODUCT.CATEGORY_ID)
              .fetch();

Check your understanding

What does the compiler catch that a SQL string would not?

Show answer

A renamed column or a type mismatch.

Practice

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