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SQLBolt – Interactive lessons and exercises to learn SQL

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Re: SQLBolt – Interactive lessons and exercises to learn SQL

#31

Post by moehm »

iamcreasy wrote: post #26
stouset wrote: post #13

Earlier quoted context omitted.

I haven’t read this yet but I love your take. Far too often do I see developers doing analytics by slurping an entire table across the network and performing calculations on it in the application. Of course it appears to work in development with tens of kilobytes of records and a local database, but as soon as it’s deployed to production it unleashes chaos. I consider myself very good at SQL but I do prefer to use OR…

I have not used ORM, but used some basic SQL. Is ORM more performant? Why should I learn SQL if I can do all the things using ORM?

Quite the contrary, ORMs in general are less performant. Using ORMs boils down to two things, convenience and the ability to switch the underlying RDBMS. (For example all the OSS which says you can choose between MySQL, Postgres or SQLite.)

But if you support all RDBMS you only can support the smallest intersection between them and can't use advanced features like CTE, window functions, JSON support etc.

Re: SQLBolt – Interactive lessons and exercises to learn SQL

#32

Post by lolive »

qwerty456127 wrote: post #21

SQL is both slightly ugly (which I attribute to the historical decision to use natural language words instead of the mathematical symbols of the relational algebra notation - the symbols make the expressions more readable once you learn them) and very beautiful. I'm sad most of the people have forgotten it and prefer to use ORMs today. Most often (except when coding a stupid low-feature phonebook/todolist tutorial) i…

From what I remember, I used to write a lot of JPQL, when I had to to do some Hibernate stuff. isn't it standard way to use ORM? (or do people really traverse their connected objects, creating a load of n+1 select?)

Re: SQLBolt – Interactive lessons and exercises to learn SQL

#33

Post by dragonwriter »

moehm wrote: post #31
iamcreasy wrote: post #26

Earlier quoted context omitted.

I have not used ORM, but used some basic SQL. Is ORM more performant? Why should I learn SQL if I can do all the things using ORM?

Quite the contrary, ORMs in general are less performant. Using ORMs boils down to two things, convenience and the ability to switch the underlying RDBMS. (For example all the OSS which says you can choose between MySQL, Postgres or SQLite.) But if you support all RDBMS you only can support the smallest intersection between them and can't use advanced features like CTE, window functions, JSON support etc.

> But if you support all RDBMS you only can support the smallest intersection between them and can't use advanced features like CTE, window functions, JSON support etc.

That's not true at all, any more that it’s true of supporting all browsers with JS. You can use the advanced features where available, and implement logically (if not performance)-equivalent functionality using more basic functions where the advanced features aren’t available.

Or, if you are lazy, just have a reduced feature set available with less capable RDBMS engines. But, on any case, its simply not the case that an ORM that supports engines of varying capacity is limited to using only the least-common-denominator feature set.

Re: SQLBolt – Interactive lessons and exercises to learn SQL

#34

Post by dspillett »

reedf1 wrote: post #11

I'm of the firm opinion that you can have a very successful career purely as an SQL genie.

Not purely, I do other data related dev & admin work, and other infrastructure & security stuff[†], but I do fairly well out of being the senior[‡] around here who gets passed the nasty SQL problems (which usually turn out to be a missing index, or complex statements entirely consisting of non-sargable predicates that can be easily rearranged with a little thought, but are sometimes more interesting).

[†] I used to be considered completely “full stack” but that was numerous years ago, and I enjoy my non-techie hobbies too much to have time to keep up-to-date with everything!

[‡] “senior” as in citizen…

Re: SQLBolt – Interactive lessons and exercises to learn SQL

#35

Post by linspace »

blowski wrote: post #9

My favorite book for learning SQL is “The Art of PostgreSQL”. https://theartofpostgresql.com/ I found the combination of real-world problems, general SQL advice, and the broad range of topics to be a really good book. It took my SQL from “the database is not much more than a place to persist application data” to “the application is not much more than a way to match commands to the database”. It’s amazing how much bes…

Solving a programming problem is usually finding the right data structure, so in that sense is not surprising. Most of the time I find that the real work is simply performed by the DB, and it's not just persistence, it's mantaining state and managing communication in concurrent applications.

Re: SQLBolt – Interactive lessons and exercises to learn SQL

#36

Post by wirthjason »

omega3 wrote: post #20
blowski wrote: post #9

My favorite book for learning SQL is “The Art of PostgreSQL”. https://theartofpostgresql.com/ I found the combination of real-world problems, general SQL advice, and the broad range of topics to be a really good book. It took my SQL from “the database is not much more than a place to persist application data” to “the application is not much more than a way to match commands to the database”. It’s amazing how much bes…

That's one of the most expensive technical books I've ever seen.

Holy smokes, $100?!?! You’re not kidding!

I’m always willing to buy technical books. I think it’s valuable to have material from different authors because they each have different perspectives and styles. E.g. CLRS vs Sedgewick vs Skiena. I also like to support the authors. However I’ll take a hard pass at this one.

My ability to level up is rarely due to the quality of the material, it’s more a function of how much time and effort into studying and learning. Time is the limiting factor in almost everything, not learning material.

In other words, learning isn’t about choosing “book A” vs “book B” but rather studying any books vs scrolling through HN, watching YouTube, or any of the other million blackholes of time.

Re: SQLBolt – Interactive lessons and exercises to learn SQL

#37

Post by xonar »

blowski wrote: post #9

My favorite book for learning SQL is “The Art of PostgreSQL”. https://theartofpostgresql.com/ I found the combination of real-world problems, general SQL advice, and the broad range of topics to be a really good book. It took my SQL from “the database is not much more than a place to persist application data” to “the application is not much more than a way to match commands to the database”. It’s amazing how much bes…

I'm thinking now about buying this because of your comment, but I'm wondering if full edition is worth extra 50$ compared to standard

Re: SQLBolt – Interactive lessons and exercises to learn SQL

#38

Post by blowski »

xonar wrote: post #37
blowski wrote: post #9

My favorite book for learning SQL is “The Art of PostgreSQL”. https://theartofpostgresql.com/ I found the combination of real-world problems, general SQL advice, and the broad range of topics to be a really good book. It took my SQL from “the database is not much more than a place to persist application data” to “the application is not much more than a way to match commands to the database”. It’s amazing how much bes…

I'm thinking now about buying this because of your comment, but I'm wondering if full edition is worth extra 50$ compared to standard

It really depends how much $50 is worth to you. The book is brilliant by itself, but the datasets and unit test examples are a really good tool for playing with. Maybe if you have some data from a real-world project you could use that instead.

Re: SQLBolt – Interactive lessons and exercises to learn SQL

#39

Post by blowski »

moehm wrote: post #31
iamcreasy wrote: post #26

Earlier quoted context omitted.

I have not used ORM, but used some basic SQL. Is ORM more performant? Why should I learn SQL if I can do all the things using ORM?

Quite the contrary, ORMs in general are less performant. Using ORMs boils down to two things, convenience and the ability to switch the underlying RDBMS. (For example all the OSS which says you can choose between MySQL, Postgres or SQLite.) But if you support all RDBMS you only can support the smallest intersection between them and can't use advanced features like CTE, window functions, JSON support etc.

I use Postgres window functions with Hibernate and Doctrine, plus lots of other Postgres-specific functionality.

The real benefit of the ORM to me are that:

* some query results are cached

* the "unit of work" pattern allows me to distribute changes to an entity and then commit it as a transaction.

Anyway, the ability to suddenly switch RDBMS only works out in practice if you actively maintain support for multiple engines.

Re: SQLBolt – Interactive lessons and exercises to learn SQL

#40

Post by blowski »

wirthjason wrote: post #36
omega3 wrote: post #20

Earlier quoted context omitted.

That's one of the most expensive technical books I've ever seen.

Holy smokes, $100?!?! You’re not kidding! I’m always willing to buy technical books. I think it’s valuable to have material from different authors because they each have different perspectives and styles. E.g. CLRS vs Sedgewick vs Skiena. I also like to support the authors. However I’ll take a hard pass at this one. My ability to level up is rarely due to the quality of the material, it’s more a function of how much…

I look at it that I spent $100 on this book, and got a $20K payrise. At that order of magnitude, the difference between spending $10 and $100 didn't matter.
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