Translate this SQL to jOOQ - sql

Question

I'm failing to translate this SQL into working jOOQ:
SELECT * FROM product p JOIN
( SELECT * FROM
(SELECT max(product_rev_id) as maxi
FROM product_rev
GROUP BY product_id) as a
JOIN product_rev as t ON t.product_rev_id = maxi
WHERE valid_to IS NOT NULL
) as z ON z.product_id = p.product_id
WHERE p.product_id in(1,2,3,4,5);
Here's the SQL-Fiddle:
http://sqlfiddle.com/#!9/d7816/1
I tried several hours, but it's getting a mess with all that aliases and jOOQ.

Answer 1

The easiest way to translate such nested queries to jOOQ is by looking at jOOQ sub queries as composable, reusable elements. I.e.
// Assuming this
import static org.jooq.impl.DSL.*;
// Then write the inner-most derived table
Table<?> a = table(
select(max(PRODUCT_REV.PRODUCT_REV_ID).as("maxi"))
.from(PRODUCT_REV)
.groupBy(PRODUCT_REV.PRODUCT_ID)
).as("a");
// Then use a in the middle derived table
ProductRev t = PRODUCT_REV.as("t");
Table<?> z = table(
select()
.from(a)
.join(t).on(t.PRODUCT_REV_ID.eq(a.field("maxi", PRODUCT_REV.PRODUCT_REV_ID.getType())))
.where(t.VALID_TO.isNotNull())
).as("z");
// Finally, the outer-most query
Product p = PRODUCT.as("p");
DSL.using(configuration)
.select()
.from(p)
.join(z).on(z.field(PRODUCT_REV.PRODUCT_ID).eq(p.PRODUCT_ID))
.where(p.PRODUCT_ID.in(1, 2, 3, 4, 5))
.fetch();
Alternative, using views
From your query, I suspect that the only really dynamic part is
WHERE p.product_id in (1, 2, 3, 4, 5)
This means that you might as well create a view in your database for the rest of the query, and query that view from your client.