A lot of material I've seen has been like the classic image of "How to draw an owl. First draw two circles, then draw the rest of the owl", where they tell you the super basic stuff, then assume you know everything.
Having an understanding of relational algebra (not the symbols, but the concept; math is always about the concept) generally helps a lot as well; it's the reason why compsci database lectures often start with relational algebra.
> We would like to find the total weight of cats grouped by age. But only return those groups with a total weight larger than 12.
The total weight of cats grouped by age.
SELECT sum(weight), age
FROM cats
GROUP BY age
SELECT sum(weight), age
FROM cats
GROUP BY age
HAVING sum(weight) > 12
SELECT sum(weight), age
FROM cats
GROUP BY age
HAVING sum(weight) > 12
ORDER BY age
SELECT sum(weight) AS total_weight, age
FROM cats
GROUP BY age
HAVING sum(weight) > 12
ORDER BY ageI can also recommend Learning SQL by Alan Beaulieu, which was recommended in some HN comment. After looking into various books, some of them Postgres specific, I found this one to be the best for learning from scratch.
https://www.red-gate.com/simple-talk/sql/t-sql-programming/w...
[EDIT]
I created an issue for this here: https://github.com/ibis-project/ibis/issues/1597