How to use stringstream to separate comma separated strings [duplicate]. Ubuntu 20.04 best way to make file server? Comma definition, the sign (,), a mark of punctuation used for indicating a division in a sentence, as in setting off a word, phrase, or clause, especially when such a division is accompanied by a slight pause or is to be noted in order to give order to the sequential elements of the sentence. How did my 4 Tesla shares turn into 12 shares? To me, flexibility (in such cases) == no discipline == laziness. When used carefully, denormalization can be just the right thing to do for a certain query you are trying to optimize, but it must be done with full understanding that it harms other queries. There's very few "horrible" ideas in sw development - mostly they're just ideas with very limited applicability. SQL Antipatterns: Avoiding the Pitfalls of Database Programming, postgresql.org/docs/current/static/arrays.html, querying an XML list in sql server using Xquery, Can’t ensure that each value is the right data type: no way to prevent. Depending on ui, values can be split[] e.g. Online word processor for the novelist, blogger, writer needing synonyms. And probably this is why it never lead to problem in C# / Java. You've managed to get away with it, but the cost of your few minutes of development time has cost you lousy query performance, flexibility, and maintainability of your code. Now, I know that the correct solution would be to create a second table and properly normalize the database. I needed a multi-value column, it could be implemented as an xml field, It could be converted to a comma delimited as necessary. How do I iterate over the words of a string? Easiest way to convert int to string in C++. I'm also asking because I'm thinking about cleaning up the program and make it more maintainable. SQL injection and database normalisation are orthogonal topics, and your digression on injection is irrelevant to the question. You might be misreading cultural styles. to check checkboxes in a list from driver table in least common scenario without having to go to another table to get them. So the stringstream::>> operator can separate strings by space but not by comma. Where is the line at which the producer of a product cannot be blamed for the stupidity of the user of that product? A second criticism is that putting raw input results directly into a database, without any validation or binding at all, leaves you open to SQL injection attacks. Can’t enforce uniqueness: no way to prevent. In general anything can be defensible if it meets the requirements of your project. The only reason you should do something like this is that you know how to do it "the right way" but you have come to the conclusion that there is a tangible reason not to do it that way. Perhaps you could have found a middle ground and used an integer representing a set of bit flags instead? My view is that if you don't like using relational databases then look for an alternative that suits you better, there are lots of interesting "NOSQL" projects out there with some really advanced features. This rings alarm bells. Hard to search for all entities with a given value in the list; you have to use an inefficient table-scan. Non-plastic cutting board that can be cleaned in a dishwasher. Join Stack Overflow to learn, share knowledge, and build your career. Once you have the proof complete, then add a database correctly. In general, storing data in this way is suboptimal (e.g. Comma-separated lists are wrong enough that I made this the first chapter in my book: SQL Antipatterns: Avoiding the Pitfalls of Database Programming. There are some things in there I'm not entirely happy with, one of them is the topic of this question. @DmitryGusarov It's a habit and a good practice. But is it a good practice to have a method outside of a class? Opt-in alpha test for a new Stacks editor, Visual design changes to the review queues. **, With CSV: Hard to join the values to the lookup table they reference.**. Some more context, this is a small internal application that essentially replaces an Excel file that was stored on a shared folder. No, it's a horrible idea. Can’t delete a value from the list without fetching the whole list. I am revising the design now that I have learnt NHibernate but back then I needed the flexibity to design the form in ASP.NET and use the textbox ids as key in the key/value pair. Why even save the data for a proof of concept? It's a defensible choice, but that doesn't make it correct or good. ah, so it sounds like the problem caused by c++ ability to have a method outside of a class. https://stackoverflow.com/questions/3653462/is-storing-a-delimited-list-in-a-database-column-really-that-bad/53566631#53566631. Prove that in a *nonlinear* circuit, adding resistor between equipotential terminals draws no current. With CSV: Storing integers as strings takes about twice as much space as storing binary integers. Cure writer’s block with built-in thesaurus, dictionary, keyword generator, and more. Vampires as a never-ending source of mechanical energy. With XML: tags are used instead of commas, In short, using XML gets around some of the issues with delimited list AND can be converted to a delimited list as needed. The main operations on a dictionary are storing a value with some key and extracting the value given the key. Placing a comma-separated list of key:value pairs within the braces adds initial key:value pairs to the dictionary; this is also the way dictionaries are written on output. https://stackoverflow.com/questions/3653462/is-storing-a-delimited-list-in-a-database-column-really-that-bad/3653541#3653541. using stringstream >> operator in if statement, StringStream input with comma delimited string - know columns apriori, Unable to use ostream << overload with stringstream no known conversion for argument 1, Using stringstream inside a loop to extract a number from few strings. Why is “using namespace std;” considered bad practice? Can’t use foreign key constraints to link values to a lookup table; no way to enforce referential integrity. It was quicker to implement the easy solution, and I wanted to have a proof-of-concept of that application quickly and without having to spend too much time on it. How did Woz write the Apple 1 BASIC before building the computer? C++ parsing an input file line into an array of objects, Issue reading multiple lines from .txt file in C++. In addition to violating First Normal Form because of the repeating group of values stored in a single column, comma-separated lists have a lot of other more practical problems:.