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brief introduction What is Mybatis? MyBatis is an excellent persistence layer framework.It supports custom SQL, stored procedures, and advanced mapping.MyBatis eliminates almost all JDBC code and the work of setting parameters and obtaining result sets.MyBatis can configure and map primitive types, interfaces and Java POJO s (Plain Old Java O ...

Introduction to Codis codis cluster Codis is a distributed Redis solution. For upper tier applications, there is no obvious difference between connecting to the Codis Proxy and connecting to the native Redis Server (unsupported command list). Upper tier applications can be used like stand-alone Redis. The lower tier of Codis will handle r ...

Article catalog 1 Overview2 example description 2.1 flashback query2.2 flashback version query2.3 flashback transaction query2.4 flashback table2.5 flashback deletion 3 expansion 1 Overview In order to recover Oracle database from misoperation quickly, Oracle has introduced flashback technology.This blog mainly shares the flashbac ...

  catalogue 1, Singleton mode 2: Factory mode 3, Abstract factory pattern 4, Summary 5, Reference website 1, Singleton mode 1. Usage scenario of singleton mode in real life: Background processing services for printers Log object for the application Connection pool for database Counters for web sites Configuration object fo ...

Singleton mode What is singleton mode Definition of Singleton pattern: a pattern in which a class has only one instance and the class can create the instance itself. For example, only one task manager can be opened in Windows, which can avoid the waste of memory resources caused by opening multiple task manager Windows, or errors such ...

1 View The difference between a view and a table: "Is the actual data saved?""Views are not tables. Views are virtual tables. Views depend on tables." 1.1 Create View CREATE VIEW <View Name>(<Column Name 1>,<Column Name 2>,...) AS <SELECT Sentence> -- Create views based on multiple tables wit ...

High performance server, network theoretical knowledge and operating system High performance server Improve server performance 1. I/O model Blocking IO (not appropriate) Program blocking and read / write function when there is no data to read, the program blocks until the data is read successfully Blocking process: the time period whe ...

1 operator 1.1 arithmetic operators meaningoperatoraddition+subtraction-multiplication*division/ 1.2 comparison operators operatormeaning=Equal to<>And ~ are not equal>=Greater than or equal to>greater than<=Less than or equal to<less than 2 exercise part 1 - query 2.1 writing the product table The SQL code is as foll ...

1. sql Title Brushing There are two main purposes to do this topic, preparing for the interview and understanding the business logic and thinking style of the data analyst in practice. Most of the data analysts are biased toward the business side, with the indicators increasing or decreasing, how to analyze, from which angles to analyze, c ...

Build table 1. Table building syntax Table creation belongs to DDL statements, including create, drop and alter create table Table name (field name 1 data type, field name 2 data type, field name 3 data type,) 2. Data type varchar: variable length string, which is slow and saves space char: fixed length string. Regardless of the actual d ...