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Take a note: The article is transferred from blog Park, original address: EF common constraint writing Invasion and deletion! 1, Configure constraints through Attribute 1. Primary key constraint Configure the primary key constraint through KeyAttribute. The code is as follows: [Key] public int PrimaryKey{ get; set; } 2. Foreign key constr ...

brief introductionCopyOnWriteArrayList is a thread safe version of ArrayList. It is also implemented internally through arrays. Each time the array is modified, a new array is completely copied to modify it. After modification, the old array is replaced. In this way, only write operations are blocked, read operations are not blocked, and read-w ...

Python notes File operation I Role of file operation Function: store some contents (data) so that the next execution of the program can be used directly without remaking. II Basic operation of files 1. Document operation steps Open fileRead and write operationsClose file Note: it can refer to opening and closing files wi ...

Oracle database operation and maintenance scheme and optimization Operation and maintenance optimization This paper explains in detail how to operate and maintain Oracle database, and explains how to operate and maintain it from all aspects. preface: In the last article, we talked about the performance optimization of Oracle database. In ...

We only look at payment here. We don't look at other things that have nothing to do with payment 1, Prepare page There are three main pages 1. The first page is the ticket purchase page 2. Second page, payment details page The three purple ones are related to our payment 3. The third page, payment success jump page 2, Prepare Q ...

Java Programming Network Programming TCP Programming Complete the development of TCP programs using Socket s Use this class to easily establish a reliable, two-way, continuous, point-to-point communication connection In Socket development, the server side uses ServerSocket to wait for the client to connect. For Java network programs, each cl ...

array 1. Array concept Array: A fixed container for storing multiple elements of the same data type in a program. Prerequisites for arrays (characteristics): 1. Once the array is initialized, its length is fixed; 2. The elements in an array must be of the same data type in memory; 3. The number of elements in the array must be multiple; ...

1. Threads 1. Definition Similar to a process, threads are a mechanism that allows applications to perform multiple tasks concurrently. ** A process can contain multiple threads. ** All threads in the same program execute the same program independently and share the same global memory area, including initialized, uninitialized, and hea ...

It is quite complex to implement advanced String classes. Unlike C++ and C#, many modules need to solve their own memory problems, and how to improve the efficiency of memory space, whether calling a function triggers a copy constructor, and how to avoid duplicate memory release when triggering a copy constructor. There are a few overloads ...

For Tribal Members Only Introduction to Tarjan algorithm The Tarjan algorithm is based on a depth-first search algorithm that defines the order number (timestamp) of the nodes where DFN(u) is the node and the order number of the earliest node that a subtree with Low(u) is the u or u can trace back to C++ code, using a chain forward star ma ...