relational-database

问题 I am going to deal with a huge amount of data in my project. I have read about big data concepts but never used it yet. But reading all those Big Data Documents I am still not sure whether my requirement needs Big Data or is it good to handle with traditional relational database. Here is some information about my DB. My main DB is a repository for different data sources. Each of this data sources deals with same kind of data (data in same domain), but some data sources contain extra fields

问题 I have created this model: Vendor_Key table contains the unique Vendor Numbers of table 1,2 and 3. The only table that has unique values is the Vendor_Key table. However, I can't get the relationships to work: PowerPivot can't identify the relationship either. Nonetheless, the relationships between Vendor_Key and Table_4 works correctly, but it doesn't when I add a field from another table. I have found these articles related to the subject, but I think this issue may more complex since I am

问题 There is a 1:1 relationship between invoices and projects in my existing schema. I am in the process of modifying it to allow for one project to have many invoices, but I also need to track payments. Currently, a single payment relates to 1 (or more) invoices (really it's an Invoice Batch). Ideally, multiple payments per invoice can be tracked. To do that, I think there needs to be a M:M relationship between invoices and payments. So, once the data is stored, how does one determine how much

问题 I'm now trying to incorporate relational database in my project. Before the implementation of rdbms in my project, normally i would normally be able to access my desired value through this code: public static string guitar { get; set; } public static List<stringInstrumentItem> GetGuitarItems() { List<stringInstrumentItem> list2 = new List<stringInstrumentItem>(); MusicStoreDBEntities obj2 = new MusicStoreDBEntities(); list2 = (from g in obj2.stringInstrumentItems where g.brand == guitar

问题 I want to design a database of basketball players and their stats. I hear star schema databases are the best for these type of tasks. If I'm not mistaken, star schema has dim and fact tables. I plan to load scores/stats into the fact tables and teams,year, coach, conference, etc in the dim tables. Is this an acceptable approach? Im a noobie at database design so please help if you can or give me your thoughts on my process. Thanks! 来源： https://stackoverflow.com/questions/24524919/star-schema

问题 An app I'm currently designing allows users to create custom competitive leagues (think of it kind of like fantasy sports) and each user can join different leagues and each league consists of multiple rounds where the users (hereafter referred to as Players) will compete and can earn points for different criteria/accomplishments established for each league. Here's some key info to note: Points are accrued across all the rounds during a league/season The custom point criteria/weight settings

问题 This question already has answers here : INNER JOIN ON vs WHERE clause (11 answers) Closed 5 years ago . What is the difference between following two SQL queries select a.id, a.name, a.country from table a left join table b on a.id = b.id where a.name is not null and select a.id, a.name, a.country from table a left join table b on a.id = b.id and a.name is not null 回答1: Base on the following two test result select a.id, a.name,a.country from table a left join table b on a.id = b.id where a

问题 Consider the following schema of a product database: Parts (pid, pname) Suppliers (sid, sname) Catalog (sid, pid) sid in Catalog is a foreign key and references Suppliers and pid in Catalog is a foreign key and references the Parts table. (s1, p1) in Catalog table shows supplier s1 produces p1 . If I want find details of Parts that are not supplied by some suppliers, how we can do this? I read some parts as follows: SELECT * FROM parts P WHERE ....... (SELECT S.sid FROM suppliers WHERE .....

问题 Below is a preview of the type of list I am talking about. What is going to happen is each user is going to have their own list that they can create. They will be able to modify the headings (Maintenance, Tire Services) and modify each item and add to it and add more rows. Here is a database design I had in mind: titles: id - name - user_id 1 - Maintenance - 1 2 - Tire Services - 1 services: id - title_id - name - user_id 1 - 1 - Wiper Blades - 1 2 - 1 - Cooling System - 1 3 - 2 - Tire

问题 I've recently worked with MongoDB and learned about its schemaless design. However, I'm confused with the term NoSQL? Why is it called that? Doesn't it use SQL or SQL-like queries? I've also read from an article that the main difference lies in how data is stored. Is this true? In the case of MongoDB, it's stored like JSON documents. Also, I'm confused why I always see 'NoSQL vs relational databases'. Aren't NoSQL databases relational? I believe documents in MongoDB are still related/linked