relational-database

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 4 years ago . I have a MySQL DB and I would like to generate its relational diagram. Is there a tool that can connect to the DB and automatically generate it for me? 回答1: Yes, DEVART's DBForge for MySQL will do this. There is a free Express edition, I'm not sure it has this functionality, but have a look at: http://www.devart

问题 Below is a simple approach to save relational database records which is working perfectly fine. I have doubt on one scenario. Before that i need to know the way i am approaching has any difficulties if the database complexity increases. Any better, efficient but simple approach? ONE to ONE: tb_student // store student details id, name, country_id (country_id foriegnkey set with id of tb_country) tb_country // store all available countries id, name [Table("tb_student")] public class Student {

问题 I have a project where I will develop an android application and a website. They both should share the same database. I am trying to explore all the options and I am really confused. Here are my requirements: 1- I need an extremely simple and EASY way. I am not trying to learn; I am just trying to get things done. 2- The database design includes relationships and foreign keys. Therefore, I need a relational database. 3- The users of the android app are limited ; as it is not an app that will

问题 Ticket Vname Nname 1 Oli Seitz 1 Andi Hofmann 2 Oli Seitz 2 Oli Schmidt 2 Tim Schmidt 3 Tim Hofmann This table represents a mapping of persons ( Vname, Nname ) and tickets ( Ticket ). Vname and Nname together identify a person, but every Person ( Vname, Nname ) can have multiple tickets ( Ticket ), and a ticket can be assigned to multiple people. The PK in this table are all three columns together. So this table should be 1NF because there is no multi dimensional data in one column. But then

问题 I have a small question concerning with how I should design my database. I have a table dogs for an animal shelter and I have a table owners. In the table dogs all dogs that are and once were in the shelter are being put. Now I want to make a relation between the table dogs and the table owners. The problem is, in this example not all dogs have an owner, and since an owner can have more than one dog, a possible foreign key should be put in the table dogs (a dog can't have more than one owner,

问题 EMPLOYEE(PERSONNAME, STREET, CITY) WORKS(PERSONNAME,COMPANYNAME, SALARY) COMPANY(COMPANYNAME, CITY) MANAGES(PERSONNAME, MANAGERNAME) Find the names of all employees in this database who do not work for First Bank Corporation (assuming that all people work for exactly one company and people are allowed to appear in the database (e.g. in employee) but not appear in works). Here I do not understand the assumption part. What does it actually mean ? 回答1: As @wildplasser pointed out: The first part

问题 I want to know if there is a way to have multiple values in a single field in a MySQL database where each value is a foreign key referencing one other table. I am designing a database with a product table and a product certification table. I am using InnoDB and foreign key constraints. The "product" table contains the details about specific instances of the product. One of the details contained in the product table is the column “product_certification_id”, which is a foreign key referencing

问题 Is there a way to distribute a (smallish) self-contained relational database along with an Windows application that does not require users to install additional dependencies such as MS Access, SQL Server, MySQL, SQLite, etc.? Only the application will be accessing the database - not users directly. 回答1: Microsoft SQL Server Compact 4.0 SQL Server Compact Edition 3.5 SQLite to name just a few. 回答2: SQL Server Compact Edition 4 回答3: I would embed SQLite in my application. There's various ways

问题 In the database world, we have normalisation. You can start with a design, crank the steps and end up with a normal form of the database. This is done on the basis of the semantics of the data and can be thought of as a series of design refactorings. In object orientated design, we have the SOLID principals and various other adhoc guidelines towards good design. Do you think it is possible to define the equivalent of normal forms for OO, such that a series of refactoring steps could move a

问题 Sorry for the title, it's difficult to explain. I need a data model similar to this: As you can see, a set can belong to both a user or a school. My problem: It should only be allowed to belong either to a user OR a school. But never both at the same time. How can I solve this problem? 回答1: Your current design is called exclusive arcs where the sets table has two foreign keys, and needs exactly one of them to be non-null. This is one way to implement polymorphic associations, since a given