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1, Trigger definition Oracle trigger is a segment of PL/SQL program code that is triggered when the user makes a specific operation on the object of Oracle database. Triggered events include DML operations on tables, DDL operations of users, database events, etc. 2, Trigger classification Triggers are divided into statement level triggers an ...

explain Linux MYCAT installation configuration to realize MySQL master-slave replication + read-write separation.In this case, you have installed MySQL master-slave replication by default. Please refer to my related articles for details.Mycat has a single server and MySQL has a master server and a slave server. There are three servers in total ...

Why persist   all the data of Redis is in memory. If it goes down suddenly, all the data will be lost. Therefore, persistence is needed to ensure that the data of Redis will not be lost due to failure. When Redis is restarted, the persistence file can be reloaded to recover the data; Redis persistence related configuration Configure in ...

Django uses object relational mapper (ORM) ¹ To access the data stored in the database In essence, the data stored in the database table is encapsulated by the Django model. A model is a python object that describes database table data. Django provides some methods that allow you to manipulate data through corresponding Python model objec ...

1, Common data types Database – > data table – > row (record): information used to describe an object Column (field): an attribute used to describe an object Common data types:effectintintegerfloatSingle precision floating point (4 bytes, 32 bits)doubleDouble precision floating point (8 bytes, 64 bits)charFixed leng ...

1 string Character array, redis string is a binary security string, which can store binary data such as pictures, as well as through Binary data compressed by tools such as messagepack or protobuffer. The internal actual storage can adopt int, embstr and raw storage according to the data characteristics of string (use object encoding key to v ...

Advanced knowledge points of MySQL (II) 3, Index optimization 1. What is an index MySQL's official definition of Index is: Index is a data structure that helps MySQL obtain data efficiently. We can get the essence of Index: Index is a data structure. It can be simply understood as: ordered fast search data structure In addition to data ...

Mysql barrier free and easy learning (IV) addition, deletion, modification and query of Mysql, CRUD quick entry Mysql barrier free learning series Mysql barrier free and easy learning (I) installation and configuration under Linux Mysql barrier free and easy learning (II) database tool DataGrid download and indefinite trial Mysql barrier f ...

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 ...

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 ...