Sorry to rain on your parade, but there is nothing in that article that is not included in the basic SQL manuals like Itzik Ben-Gan's.
Also a few things are dead wrong: the "make the haystack small" is optimization (it should be at the end, as the first rule says), the "prefer UNION ALL to UNION" is missing the context (a good dev knows what is needed, not what to prefer) and the usage of CTEs is nice, but sometimes slower that other options and in SQL slower can easily be orders of magnitude, so nice is not enough. Same for 'avoid sorting where possible, especially in subqueries' or "use composite indexes" (really? it's a basic thing, not a best practice).
In the past few months I interviewed and hired several DBAs, this list is ok-ish for a junior but a fail for a senior. I am not working for FAANG, so the bar is pretty low, this article would not even pass for a junior there.
Also a few things are dead wrong: the "make the haystack small" is optimization (it should be at the end, as the first rule says), the "prefer UNION ALL to UNION" is missing the context (a good dev knows what is needed, not what to prefer) and the usage of CTEs is nice, but sometimes slower that other options and in SQL slower can easily be orders of magnitude, so nice is not enough. Same for 'avoid sorting where possible, especially in subqueries' or "use composite indexes" (really? it's a basic thing, not a best practice).
In the past few months I interviewed and hired several DBAs, this list is ok-ish for a junior but a fail for a senior. I am not working for FAANG, so the bar is pretty low, this article would not even pass for a junior there.