relational-database

I have 2 tables, both with their own auto incremented IDs, which are of course primary keys. When I want to create a 3rd table to establish the relation between these 2 tables, I always have an error. First one is about that you can have only 1 automatically-incremented column, the second one occurs when I delete the auto_increment statement from those 2, therefore sql doesn't allow me to make them foreign keys, because of the type matching failure. Is there a way that I can create a relational table without losing auto increment features? Another possible (but not preffered) solution may be

Recently NoSQL has gained immense popularity. What are the advantages of NoSQL over traditional RDBMS ? Not all data is relational. For those situations, NoSQL can be helpful. With that said, NoSQL stands for "Not Only SQL". It's not intended to knock SQL or supplant it. SQL has several very big advantages: Strong mathematical basis. Declarative syntax. A well-known language in Structured Query Language (SQL). Those haven't gone away. It's a mistake to think about this as an either/or argument. NoSQL is an alternative that people need to consider when it fits, that's all. Documents can be

I'm new in SQL(still learning) and I have to create a database for a venue. A client book for a room for an event. The problem is that the clients don't always provide their name, their email, and their phone number. Most of the time it's either name and email or name and phone. It's rarely all 3 but it happens. I need to store each of these in their respective attribute (name, email, phone). But the way they give me their info, I have a lot of null values. What can I do with these nulls? I've been told that it's better to not have nulls. I also need to normalize my table after that. Any

I have some questions about database design. Is there a name for this? Is it good practice? Any performance considerations? I have a generic table structure used to store relationships. Recently I refactored some things to use this generic structure instead of direct Fk columns, but now I'm not sure if that was really the best idea. Original Schema: +------------------+ +---------------------+ +----------------------+ | Book | | Note | | MetaParent | |------------------| |---------------------| |----------------------| | Id | | Id | | Id | | NoteId | | MetaParentId:(Null) | | MetaTableId | | +

In a fairly animated discussion in my team I was made to think what most people like as primary keys. We had the following groups- Int/ BigInt which autoincrement are good enough primary keys. There should be at least 3 columns that make up the primary key. Id, GUID and human readable row identifiers all should be treated differently. What's the best approach for PKs? It would be awesome if you could justify your opinion. Is there a better approach that the above? EDIT: Anyone has a simple sample/algorithm to generate human readable identifiers for rows that scales well? If you're going to be

So I am trying to design a database that will allow me to connect one product with multiple categories. This part I have figured. But what I am not able to resolve is the issue of holding different type of product details. For example, the product could be a book (in which case i would need metadata that refers to that book like isbn, author etc) or it could be a business listing (which has different metadata) .. How should I tackle that? This is called the Observation Pattern. Three objects, for the example Book Title = 'Gone with the Wind' Author = 'Margaret Mitchell' ISBN = '978-1416548898'