• Diagramas Entidad - Relación (Draw.io)
• Subconjuntos: <,>, <=, >=, =, <>
• Cláusulas EXISTS, NOT EXISTS, IN
• Cláusula INNER JOIN
• Cláusulas LEFT JOIN, RIGHT JOIN, FULL JOIN
• Cláusulas UNION, UNION ALL
• Cláusula CROSS JOIN
• Funciones

select * from Products p
inner join Categories c on (c.CategoryID = p.CategoryID) 

select *
from Products
where UnitPrice > (select AVG(UnitPrice) from Products)

select *
from Products
where UnitPrice <> (select AVG(UnitPrice) from Products)
-- <> sinifica diferente

select * from Products p
inner join Categories c on (c.CategoryID = p.CategoryID)
where c.CategoryName = 'Condiments'

select * from Products p
where exists (select * from Categories c
where c.CategoryName = 'Condiments'
and c.CategoryID = p.CategoryID)