Tag:Primary key

  • Net core project construction based on restful API + swagger project


    In the previous. Net core project development environment construction, it mainly introduces the construction of the project development environment. This paper mainly introduces the construction of webapi and integration swagger under. Net core, and introduces some habits of programming. Project structure In fact, the project structure is basically the same. Controller: contract of external exposure […]

  • Net core configuration, database access and other operations


    In the previous. Net core project construction based on restful API + swagger project, it mainly introduces the basic construction of the project webapi. This paper mainly focuses on some common operation methods in the development process Configuration read It’s a bit troublesome to read the configuration under. Net coreSystem.Configuration.dll, so you need to refer […]

  • Feign declarative service call of spring cloud series


    Original link:https://mrhelloworld.com/posts/spring/spring-cloud/feign-declarative-service-call/ What is feign    Feign is a lightweight restful HTTP service client in the spring cloud Netflix component. It implements the open source framework of load balancing and rest call, encapsulates the ribbon and resttemplate, realizes the interface oriented programming of web service, and further reduces the coupling degree of the project. Feign […]

  • MySQL last_sql_errno: 1062 —- classic error, primary key conflict


    1、 Basic information 1. Centos7.4 2.MySQL 5.7.21 3. Gtid based replication 2、 Exception description The slave node is mistakenly used as the master node to insert a piece of data. The same data has been inserted once in both the master and slave nodes, resulting in primary key conflict and SQL thread exception under slave. […]

  • C ා web API file online preview


    Recently, I am writing a mobile API interface. One of the requirements is that the interface returns the URL address of the attachment to let the mobile call to realize online preview of the file. General implementation idea: convert doc, xls and other text format files into PDF, and store the converted PDF file on […]

  • Netcore3.0 + webapi to front end Vue (back end)


      The first step is to create an API project     Creation complete start F5!! Pictured   Database I use Mysql to operate data with EF Development environment: win10 + vs2019MySQL server version: 8.0.16   1. Download and install plug-ins (required) MySQL-Connector-net-6.9.12 MySQL for Visual Studio 2.0.5 Use nuget to install mysql.data.entity-6.9.12 (mysql.data.entityframeworkcore. Design!! […]

  • Share your PHP functions


    Share some PHP functions written by bloggers Close to work, there are about 20 minutes left. I have nothing to do with my hand. I want to share some functions with you. Super easy to use! Intercept string function /** *@ param string $begin start string *@ param string $end end end string *@ param […]

  • Ora-14061: cannot change data type or length of index partition column


    Error occurred when modifying the primary key of partition table: Error starting command on line: 2-alter table KC23 modify AAZ210 VARCHAR2(50)Error reporting–SQL error: ora-14061: cannot change data type or length of index partition column14061. 00000 –  “data type or length of an index partitioning column may not be changed”*Cause:    User issued ALTER TABLE statement attempting […]

  • Laravel pit Diary – missing pivot model ID


    Antecedents Recently, the back-end project of the company has been upgraded from the previous version of laravel 5.6 to the version of laravel 5.8. After the upgrade, there are many SQL execution errors in the system. However, the system runs well in the old version, resulting in today’s pit digging trip. Project environment Old system […]

  • The difference between SQL Server primary key and unique constraint


    First of all, the primary key is also called the primary key constraint. It is also a constraint. Look at the creation syntax of it and the unique constraint: alter table Person add constraint PK_Id primary key (Id) alter table Person add constraint UQ_Name unique (Name) Both primary key and unique constraint require unique field […]

  • SQL Server create constraint diagram (unique primary key)


    There are five constraints in SQL Server: primary key constraint, foreign key constraint, unique constraint, default constraint and check constraint. Today, SQL Server 2008 is used to demonstrate the creation and use of these constraints. What is a primary key? In a database, it is often not just a table, and these tables are not […]

  • Clustered index and non clustered index (also called level two index)


    Difference Clustered index: put the data storage and index together, and find the index to find the dataNon clustered index: the data is stored in an index separated structure. The leaf node of the index structure points to the corresponding row of the data. MyISAM caches the index into memory first through key buffer. When […]