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I am forever grateful that I took a full semester of database design in my undergrad. This single skill has stood with me for my entire career so far and has en

I am forever grateful that I took a full semester of database design in my undergrad. This single skill has stood with me for my entire career so far and has enabled me to figure out the root cause of many production issues. Plus people really like it when you can answer ad-hoc questions like "what inspections are still open and when were they first opened". If y'all can understand Angular / React / Vue there's no reason to not learn databases.

throw345hn 6y ago
Could you suggest resources (books, articles, videos, moocs or others) to learn good database design. I am picking up skills about sql but want to better understand and learn about databases. As someone who doesnt have that background, a lot of the times I am just googling for stuff and just trying out bits and pieces.
- EvanAnderson 6y ago
  Apparently there's a 4th edition coming, but if you like the form-factor of a book-length text I'd throw a recommendation to "Database Design for Mere Mortals"[1]. I read the 1st edition from the late 90's, but I'd imagine it's still just as good. It approaches database modeling from a practical non-technical perspective, and I found it helped me learn data modeling in a software-agnostic manner, and later to influence how I talked to non-technical audiences about data modeling. I'm really glad to have found it early in my career. I will echo what others have said. Data modeling is a force-multiplier type of skill. Combine it with a reasonable understanding of SQL and you can return a lot of value very quickly. [1] https://www.amazon.com/Database-Design-Mere-Mortals-Hands/dp/0321884493 https://www.amazon.com/Database-Design-Mere-Mortals-Hands/dp...
  - ticmasta 6y ago
    Not required, but knowing a little relational algebra helps queries make a lot more sense. A lot of the features like constraints and indices are very thin veneer over the underlying concepts. At the other end of the spectrum, once you can write a few basic queries check out something like SQL Murder Mystery https://mystery.knightlab.com/ https://mystery.knightlab.com/ This one is super-fun and lets you practice some basic to low-intermediate skills.
    - fizixer 6y ago
      Fun fact: You can do relational algebra on plain text data (e.g., csv, as well as output of commands like ls, etc.) using only shell + piping + well-known shell tools.
- mcny 6y ago
  I'd like to know this as well. I think you'll just have to build things (potentially horribly) and fail. I took three semesters of database (granted, baby database classes) and I still have no idea how you can do something pretty straightforward like creating a room reservation system. If there is a reservation beginning at 10:15 AM and ending at 12:30 PM and someone tries to book a reservation from 10:00 AM to 10:30 AM, the transaction should fail. and before someone screams db2! yes, db2 can. but then you'd have to use db2 https://www.ibm.com/support/knowledgecenter/SSEPGG_11.1.0/com.ibm.db2.luw.sql.ref.doc/doc/r_overlaps_predicate.html https://www.ibm.com/support/knowledgecenter/SSEPGG_11.1.0/co... Why is this so difficult...
  - IvanVergiliev 6y ago
    Exclude constraint on a GiST index? https://stackoverflow.com/a/51247705 https://stackoverflow.com/a/51247705
  - sk5t 6y ago
    The documentation for Postgresql range types describes how to do exactly this. https://www.postgresql.org/docs/11/rangetypes.html#RANGETYPES-CONSTRAINT https://www.postgresql.org/docs/11/rangetypes.html#RANGETYPE... Edit: and if you didn't want to use postgres, you could have "starttime" and "endtime" columns and reject any bad bookings with a before insert / before update trigger.
    - gavinray 6y ago
      This approach is the best and works really well if you don't need to do a join on a related table to look up information. If you need to use data outside of the current table for exclusions/check constraints, you have to write a trigger function (as far as I know). I had to solve this recently, where the actual start/end times were stored on a related table. I'm no SQL wizard, but I'd love to share my solution in case it helps others (it might be terrible). Note: I changed the actual tables/domain to be generic, this is a poor example and it made more sense for my usecase, but this shows general approach. -- Let's pretend we have these tables (awful design, but for sake of example): -- room <-> reservation <-> reservation_info -- Where "reservation_info" has "start_time" and "end_time" CREATE FUNCTION check_for_overlapping_reservations() RETURNS trigger LANGUAGE plpgsql AS $$ BEGIN IF ( -- Find the newly created reservation and join it with the info record to grab "start_time" and "end_time" for check below with this_reservation as ( select * from reservation inner join reservation_info on reservation_info.id = reservation.reservation_info_id where reservation.id = NEW.id ), bookings_for_timerange as ( -- Select every other reservation, where the reservation is happening in the same room select * from reservation as other_reservation, this_reservation inner join reservation_info as other_reservation_info on other_reservation_info.id = other_reservation.reservation_info_id where other_reservation.room_id = this_reservation.room_id AND -- And the timerange from start to end overlaps the newly created record tstzrange(this_reservation.start_time, this_reservation.end_time) && tstzrange(other_reservation_info.start_time, other_reservation_info.end_time) -- Get a count of all the records, it should only be 1. If it's greater than one, there's overlap. select count(*) from bookings_for_timerange ) > 1 THEN RAISE EXCEPTION 'Room is already reserved during this time period'; END IF; RETURN NEW; END;$$;
- ytjohn 6y ago
  The Art of Postgresql. As the title suggests, it's targeted for Postgresql. However it has a full section on data modeling, another section on data types. It's packed with lots of examples and reasoning. I feel it gives you a good mix of theoretical background and hands on immediate experience. You'll find your way around what is (in my worthless opinion) the best database engine, and the pgsql specific examples will mostly translate to other relational databases. https://theartofpostgresql.com/ https://theartofpostgresql.com/
- chadcmulligan 6y ago
  If you can find a copy of this, I'd recommend it "Conceptual Schema and Relational Database Design: A Fact Oriented Approach" by Nijssen and Halpin. They presented a richer model (NIAM) for designing databases than the ER model by Codd/Date, though CJ Dates book is useful to. Both of these are out of print now, but anything by Halpin or Date would be a useful addition. To design databases relational theory and normal forms are the language you'd need to understand - they're not very hard though seems they aren't as widely taught any more.
- woolcap 6y ago
  Just about anything written by C. J. Date would be worth your while in this regard. It will give you a solid grounding in the relational model, which you can then apply to any RDBMS. Here's a good list to start with: - Database in Depth, O'Reily (2005) - Relational Theory for Computer Professionals, O'Reilly (2013) - SQL and Relational Theory, 3rd Ed, O'Reily (2015) - Database Design and Relational Theory, 2nd Ed, Apress (2019)
shoguning 6y ago
Pardon my ignorance--is inspections some concept that relates to database management, or are you referring to a query like "select * from inspections where status = 'open';". Honestly asking.
- crgwbr 6y ago
  I believe OP is just referring to the ability to run adhoc queries. Typically nosql solutions are built to be performt for common access patterns, at the expense of being difficult or impossible to query in unplanned ways. SQL DBs are very good in that regard.
  - shoguning 6y ago
    Thanks! And yes, I agree. The ability to write ad hoc SQL is a great skill.
    - jonathanzufi 6y ago
      Totally. I’ve always admired SQL wizards and their ability to (quickly) produce the most optimal queries given the relatively limited syntax (compared to what you can do with frameworks like, for example, LINQ today).
- SamuelAdams 6y ago
  Ah yes, inspections in this context means Safety Inspections, aka a business rule or thing. Industry is Retail / Grocery. Inspectors inspected food at stores on day one and Stores had 5 business days to “complete” the inspection. Internal audit wanted a list of “defaulted” inspections so they could go harass the store people to get their things done.
cgh 6y ago
Absolutely agree. Learning data normalisation was up there with Typing 9 (touch-typing class in grade 9, not Hindley-Milner whatever) in terms of long-term usefulness.
Noumenon72 6y ago
Is "inspections" a typo for "transactions" here?
dugmartin 6y ago
I feel the same way. It’s been nearly 30 years since my undergrad database class and I used what I learned in that class yesterday mocking out a schema for a personal project. We didn’t touch any real dbms in the class but rather did most of the class work using relational algebra.

throw345hn 6y ago

Could you suggest resources (books, articles, videos, moocs or others) to learn good database design. I am picking up skills about sql but want to better understand and learn about databases. As someone who doesnt have that background, a lot of the times I am just googling for stuff and just trying out bits and pieces.

EvanAnderson 6y ago
Apparently there's a 4th edition coming, but if you like the form-factor of a book-length text I'd throw a recommendation to "Database Design for Mere Mortals"[1]. I read the 1st edition from the late 90's, but I'd imagine it's still just as good. It approaches database modeling from a practical non-technical perspective, and I found it helped me learn data modeling in a software-agnostic manner, and later to influence how I talked to non-technical audiences about data modeling. I'm really glad to have found it early in my career. I will echo what others have said. Data modeling is a force-multiplier type of skill. Combine it with a reasonable understanding of SQL and you can return a lot of value very quickly. [1] https://www.amazon.com/Database-Design-Mere-Mortals-Hands/dp/0321884493 https://www.amazon.com/Database-Design-Mere-Mortals-Hands/dp...
- ticmasta 6y ago
  Not required, but knowing a little relational algebra helps queries make a lot more sense. A lot of the features like constraints and indices are very thin veneer over the underlying concepts. At the other end of the spectrum, once you can write a few basic queries check out something like SQL Murder Mystery https://mystery.knightlab.com/ https://mystery.knightlab.com/ This one is super-fun and lets you practice some basic to low-intermediate skills.
  - fizixer 6y ago
    Fun fact: You can do relational algebra on plain text data (e.g., csv, as well as output of commands like ls, etc.) using only shell + piping + well-known shell tools.
mcny 6y ago
I'd like to know this as well. I think you'll just have to build things (potentially horribly) and fail. I took three semesters of database (granted, baby database classes) and I still have no idea how you can do something pretty straightforward like creating a room reservation system. If there is a reservation beginning at 10:15 AM and ending at 12:30 PM and someone tries to book a reservation from 10:00 AM to 10:30 AM, the transaction should fail. and before someone screams db2! yes, db2 can. but then you'd have to use db2 https://www.ibm.com/support/knowledgecenter/SSEPGG_11.1.0/com.ibm.db2.luw.sql.ref.doc/doc/r_overlaps_predicate.html https://www.ibm.com/support/knowledgecenter/SSEPGG_11.1.0/co... Why is this so difficult...
- IvanVergiliev 6y ago
  Exclude constraint on a GiST index? https://stackoverflow.com/a/51247705 https://stackoverflow.com/a/51247705
- sk5t 6y ago
  The documentation for Postgresql range types describes how to do exactly this. https://www.postgresql.org/docs/11/rangetypes.html#RANGETYPES-CONSTRAINT https://www.postgresql.org/docs/11/rangetypes.html#RANGETYPE... Edit: and if you didn't want to use postgres, you could have "starttime" and "endtime" columns and reject any bad bookings with a before insert / before update trigger.
  - gavinray 6y ago
    This approach is the best and works really well if you don't need to do a join on a related table to look up information. If you need to use data outside of the current table for exclusions/check constraints, you have to write a trigger function (as far as I know). I had to solve this recently, where the actual start/end times were stored on a related table. I'm no SQL wizard, but I'd love to share my solution in case it helps others (it might be terrible). Note: I changed the actual tables/domain to be generic, this is a poor example and it made more sense for my usecase, but this shows general approach. -- Let's pretend we have these tables (awful design, but for sake of example): -- room <-> reservation <-> reservation_info -- Where "reservation_info" has "start_time" and "end_time" CREATE FUNCTION check_for_overlapping_reservations() RETURNS trigger LANGUAGE plpgsql AS $$ BEGIN IF ( -- Find the newly created reservation and join it with the info record to grab "start_time" and "end_time" for check below with this_reservation as ( select * from reservation inner join reservation_info on reservation_info.id = reservation.reservation_info_id where reservation.id = NEW.id ), bookings_for_timerange as ( -- Select every other reservation, where the reservation is happening in the same room select * from reservation as other_reservation, this_reservation inner join reservation_info as other_reservation_info on other_reservation_info.id = other_reservation.reservation_info_id where other_reservation.room_id = this_reservation.room_id AND -- And the timerange from start to end overlaps the newly created record tstzrange(this_reservation.start_time, this_reservation.end_time) && tstzrange(other_reservation_info.start_time, other_reservation_info.end_time) -- Get a count of all the records, it should only be 1. If it's greater than one, there's overlap. select count(*) from bookings_for_timerange ) > 1 THEN RAISE EXCEPTION 'Room is already reserved during this time period'; END IF; RETURN NEW; END;$$;
ytjohn 6y ago
The Art of Postgresql. As the title suggests, it's targeted for Postgresql. However it has a full section on data modeling, another section on data types. It's packed with lots of examples and reasoning. I feel it gives you a good mix of theoretical background and hands on immediate experience. You'll find your way around what is (in my worthless opinion) the best database engine, and the pgsql specific examples will mostly translate to other relational databases. https://theartofpostgresql.com/ https://theartofpostgresql.com/
chadcmulligan 6y ago
If you can find a copy of this, I'd recommend it "Conceptual Schema and Relational Database Design: A Fact Oriented Approach" by Nijssen and Halpin. They presented a richer model (NIAM) for designing databases than the ER model by Codd/Date, though CJ Dates book is useful to. Both of these are out of print now, but anything by Halpin or Date would be a useful addition. To design databases relational theory and normal forms are the language you'd need to understand - they're not very hard though seems they aren't as widely taught any more.
woolcap 6y ago
Just about anything written by C. J. Date would be worth your while in this regard. It will give you a solid grounding in the relational model, which you can then apply to any RDBMS. Here's a good list to start with: - Database in Depth, O'Reily (2005) - Relational Theory for Computer Professionals, O'Reilly (2013) - SQL and Relational Theory, 3rd Ed, O'Reily (2015) - Database Design and Relational Theory, 2nd Ed, Apress (2019)

shoguning 6y ago

Pardon my ignorance--is inspections some concept that relates to database management, or are you referring to a query like "select * from inspections where status = 'open';". Honestly asking.

crgwbr 6y ago
I believe OP is just referring to the ability to run adhoc queries. Typically nosql solutions are built to be performt for common access patterns, at the expense of being difficult or impossible to query in unplanned ways. SQL DBs are very good in that regard.
- shoguning 6y ago
  Thanks! And yes, I agree. The ability to write ad hoc SQL is a great skill.
  - jonathanzufi 6y ago
    Totally. I’ve always admired SQL wizards and their ability to (quickly) produce the most optimal queries given the relatively limited syntax (compared to what you can do with frameworks like, for example, LINQ today).
SamuelAdams 6y ago
Ah yes, inspections in this context means Safety Inspections, aka a business rule or thing. Industry is Retail / Grocery. Inspectors inspected food at stores on day one and Stores had 5 business days to “complete” the inspection. Internal audit wanted a list of “defaulted” inspections so they could go harass the store people to get their things done.

cgh 6y ago

Absolutely agree. Learning data normalisation was up there with Typing 9 (touch-typing class in grade 9, not Hindley-Milner whatever) in terms of long-term usefulness.

Noumenon72 6y ago

Is "inspections" a typo for "transactions" here?

dugmartin 6y ago

I feel the same way. It’s been nearly 30 years since my undergrad database class and I used what I learned in that class yesterday mocking out a schema for a personal project. We didn’t touch any real dbms in the class but rather did most of the class work using relational algebra.