Programming VIP

1, Logical operator Logical operators are mainly used to judge whether an expression is true or false. In mysql, the return result of logical operators is 1, 0 or NULL. MySQL supports four logical operators as follows: 1.1 logical non operator Logical non (NOT or!) Operator means to return 1 when the given value is 0Returns 0 when the g ...

catalogue Foreword 1.LAMP introduction and overview 2.Apache 2.1Apache origin 2.2 introduction to Apache 3.httpd  3.1 compiling and installing httpd server 3.2 compiling and installing httpd server 4. Install MYSQL 4.1 installing MYSQL 4.2sql_ The common values of mode are as follows: 4.3 setting environment variables  5. Inst ...

Chapter 7 single line function 1. Understanding of function 1.1 what is a function Function runs through the use of computer language. What is the role of function? It can encapsulate the code we often use and call it directly when necessary. This not only improves the code efficiency, but also improves the maintainability. In SQL, we can al ...

MySQL -- index creation principle 1. Data preparation Create database and table create database if not exists testindexdb; use testindexdb; create table student_info( id int(11) not null auto_increment, student_id int(11) not null , name varchar(20) default null, course_id int not null , class_id int(11) defaul ...

Mybatis annotation development single table operation 1. Common notes of mybatis In recent years, annotation development has become more and more popular. Mybatis can also use annotation development, which can be used to reduce the writing of Mapper Mapping file. @Insert: add @Update: implement update @Delete: delete @Select: implement q ...

(1) Clone the table and generate the data records of the data table into a new table 1. Method 1: use like create table test1 like info; #Using the LIKE method, copy the KY08 table structure to generate the test01 table insert into test1 select * from info; 2. Method 2: direct cloning CREATE TABLE test2 (SELECT * from info); show cre ...

Concepts and differences SELECT... LOCK IN SHARE MODE uses the IS lock (intention to share lock), that IS, share locks are added to the qualified rows. In this way, other sessions can read these records or continue to add IS locks, but these records cannot be modified until the execution of your locked session IS completed (otherwise, the lock ...

reference material https://www.bilibili.com/video/BV1Kr4y1i7ru?p=32&spm_id_from=pageDriver 1. Constraints 1.1 general Concept: constraints are rules that act on fields in a table and are used to limit the data stored in the table.Objective: to ensure the correctness, validity and integrity of the data in the database.classification ...

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 ...

1, Arithmetic operator Arithmetic operators are mainly used for mathematical operations. They can connect two values or expressions before and after the operator, and perform addition (+), subtraction (-), multiplication (*), division (/) and modulus (%) operations on the values or expressions. 1.1 addition and subtraction operators mys ...