deletion mapping

root object). When you delete an object instance, the data is deleted from the bottom up. What to do if you encounter a deletion from the middle. How multiple inheritance is handled. (Golden Dragon Fly) 3. Correlation mapping mode 3.1 A-to-one correlation mode: Adds a column at both ends of the association.3.2 One-to-many correlation modes: Same as 3.1. If more of this end is ordered, you also need to add

I have not seen the MATLAB has a class dict structure, this can not but say is a kind of regret. Of course, this superficial understanding, also let me earlier and Julia knot the fate, gain it. From 2010 to 2013, I was mainly using MATLAB, such as DataSet (=>table) and other data structures (Matrix, cell,struct). Recently saw a lot of people in writing related articles, specially turn, for Matlab feel happy. In fact, the dict structure of MATLAB is also some, is Hou Wei matlab should be correcte

, is that map is the fast insertion, deletion, and retrieval of data for record-type elements with key values, while set can be considered as a processing of a single data. Map creates a container's data distribution by dividing an element into a key-value section and specifying the function comparison rules for the entire element by this local key value. The element key value of map is unique and does not allow duplicate element key values to be inse

Object/Relation Mapping Object-relational database ing What is Orm? Object-Role Modeling (ORM) provides a conceptual and easy-to-understand Method for modeling data. The ORM methodology is based on three core principles: Simple: data is modeled in the most basic form. Communication: the database structure is documented in a language that anyone can understand. Accuracy: Create a correctly standardized structure based on the data model. Typically, mod

modification of the reference and collection properties in the category and product classes is used for the lazy load function of the entity Framework Code first. Without virtual decoration, lazy loading will not be enabled when an instance of the category class queries the containing product instance. Of course, the entity Framework Code first delay loading is not necessary, so the virtual modifier can also be added.After defining the above two classes, no more

User.cs:View CodeFile class Role.cs:View CodeAfter defining the above two classes, no more mapping configuration of the entity Framework Code first to the database is added, and after running, the resulting data table structure is:From the table structure above, it can be seen that, in addition to generating the users and Roles tables, the Roleusers table is generated as a mediation table, reflecting the many-to-many association relationships between

OA system once again returned to the permission system before, for the business logic of the rights system has a deeper understanding, this blog is about the OA system entity mapping and data initialization. One, Entity mapping First look at the class diagram between the entities: We can see clearly in the General class diagram, the user and the role, the role and the permission are many pairs of relatio

= "Clazzid"> Generatorclass= "Native">Generator> ID> Propertyname= "Name"column= "ClassName"> Property> Setname= "Students"Cascade= "All"Inverse= "true"> Cascade has five options: All, delete, None,save-update,delete-orphan; All: Associated operations are performed in all cases. None: Associated operations are not performed in all cases. This is the default value. Save-update: The associated operation is

,Joincolumns, Joincolumn, InversejoincolumnXml:Bidirectional:Note: Set @manytomany (mappedby= "") on a one-way basis on the other side of the collectionXML: Also set E. Component mapping: A bean that is part of a table, not as an entity, such as a student ID as part of a student entity;Component references in entities add @embeddedUsing Note: (1) bidirectional correlation Mappedby attribute must be set, XML with Indicates that the relationship is domi

Java handles large files, generally with bufferedreader,bufferedinputstream such as buffered IO classes, but if the file is oversized, the faster way is to use Mappedbytebuffer.Mappedbytebuffer is a File memory mapping scheme introduced by Java NIO, which is very high in read and write performance. The main thing about NIO is the implementation of support for asynchronous operations. One of these is that by registering a socket channel (Socketchannel)

related to management classes. of course, this is not only related to o/r m but also to the designer's design level.2. o/r m processing of the inheritance relationship.3. O/r m support for transactions.4. O/r m support for queries.The above points are only personal opinions. However, we hope to reach a consensus on some basic concepts before discussing o/r m. Otherwise, we will move further and farther away from the discussion. (Suggestion: if you do not know Oo and DP to a certain extent, it

configuring one-to-many unidirectional and bidirectional associations:Refer to one end and multi-terminal class structure reference this article: Hibernate configuration of a one-to-many association map and its cascade deletion issuesConfiguration of a one-to-many bidirectional association map (refer to the article provided above):Mapping with Add a foreign key to the private Questiontype questiontype at o

1 Collection MappingsOne buyer corresponds to multiple addressesConfiguration of the Set collectionKeep in mind that because it is a collection, the data type of the data in the collection must be written or otherwise error-List collection Configuration here is the Set Set unique difference The following configuration represents a sorted column -Configuration of the Map collectionAttention:The first thing to do when using a set map is to master the data types that must be given to the data in t

Combining BootstrapTable and KnockoutJS to implement addition, deletion, modification, and query functions [2], bootstrapknockoutjs In the previous article, I introduced the addition, deletion, modification, and query functions of BootstrapTable and KnockoutJS, and introduced some basic usage of knockout. js. Next, we will continue to introduce you through this article. If you plan to use ko for the project

VLAN ing (VLAN ing) VLAN Mapping principle introduction VLAN Mapping is also known as VLAN ing. Its main function is to replace the private network VLAN Tag in user packets with the public network VLAN Tag, make it transmitted according to the internet plan. When a packet is sent to the peer user's private network, the VLAN Tag is restored to the original user's private network VLAN Tag according to the sam

C + + Primer (Fifth edition) learning Note _9_ Standard Template Library _multimap multi-mapping containerThe multi-mapping container multimap is basically the same as the map structure, but because of the duplicate key values, the Multimap element insertion, deletion, and lookup are not the same as the map method.1. Multimap object creation, element insertionWhe

1, exactly where to use cascade= "..."?Cascade property is not a many-to-many relationship must be used, with it just let us in the insertion or deletion of the image is more convenient, as long as the cascade at the source of the insertion or deletion, all cascade relationship will be inserted or deleted by themselves. is to be able to correct cascade,unsaved-value is a very important attribute. Hibernate

OverviewOn a 32-bit system, the kernel occupies a linear address space from 3gb~ 4GB, a total of 1GB size, and the kernel directly maps the 0~896MB of the former 896MB to the physical memory, i.e. the linear mapping, which takes the remaining 128M linear address space as a window to access the memory above 896M. The main reason for the introduction of high-end memory mapping is that when we install more tha

Original:high-end memory mapping of Linux kernel notesOn a 32-bit system, the kernel uses the linear address space of section 3gb~ 4GB, a total of 1GB size. The kernel directly maps the first 896MB of the 0~896MB to the physical memory, which is a linear map that takes the remaining 128M linear address space as a window to access higher than 896M of memory.The main reason for the introduction of high-end memory ma