Programmer Think

1, MMM overview 1. What is MMM   MMM (Master Master replication manager for MySQL) is a script program that supports dual master failover and dual master daily management. Mmm is developed in Perl. It mainly monitors and manages MySQL master master replication. Although it is called dual master replication, only one master is allow ...

Table 6 constraints Non NULL constraint not null DROP TABLE IF EXISTS tb_user; #If the table exists, delete it. If you use it with caution, you will lose data CREATE TABLE tb_user( id INT AUTO_INCREMENT, NAME VARCHAR(30) UNIQUE NOT NULL, age INT, phone VARCHAR(20) UNIQUE NOT NULL, email VARCHAR(30) UNIQUE NOT NULL, PRIMARY KEY ( ...

mysql 1. Operation on Database create create database NAME character set UTF8 collate XXX; alter alter database NAME character set UTF8 collate XXX; drop drop database NAME; show show databases; 2. Table operation create create table TABLENAME( VARNAME_1 datatype not null , name varchar(10) not null, gender tinyint(1) not null default 1, pr ...

MySQL 5.7 provides a new field format json, which is probably because MySQL wants to eat all non relational and relational databases, so it has introduced this very easy-to-use format. In this way, many of our businesses based on mongoDb or clickHouse can be implemented with MySQL. Of course, version 5.7 is only the most basic version, and the ...

MySQL complex query 1. Index MySQL Index building for MySQL The efficient operation of is very important, and the index can be greatly improved MySQL Search speed. Take the table of contents page (index) of a Chinese dictionary for example. We can quickly find the required words according to the table of contents (index) sorted by pinyin, s ...

Experiment 4 Java Web Programming 1, Experimental purpose 1. Master the installation and configuration of Tomcat, a Java Web server. 2. Learn simple HTML form design and form submission. 3. Master the use of request object and session object in JSP. 2, Experimental content 1. Download and install Tomcat8 and configure it. Start the Tomcat ...

Author: duktig Blog: https://duktig.cn (first article) Excellent still work hard. May you enjoy what you give and enjoy what you get. See github knowledge base for more articles: https://github.com/duktig666/knowledge background After learning Hadoop, do you feel that writing a MapReduce program is very complex, and it requires a lot ...

catalogue environment Document purpose detailed information environment System platform: Linux x86-64 Red Hat Enterprise Linux 7 Version: 4.3.4.7 Document purpose This paper mainly introduces how to mine the database wal log through walminer, including the installation and use of wal. detailed information 1, Introduction to walminer 1. Brief ...

3, Query operation ▎ [3.1] which databases in hive are queried show databases; Before creating other databases, hive will provide a default database for us to use default   When operating HiveQL, all operations are performed in the default data without specifying the database. The database name and table name of hive are not case sensi ...

preface Hello, ladies and gentlemen, little tu started learning JDBC today, so I'd like to send you a "fresh" learning blog As we all know, Java application and database are two different systems, so how do we combine them? At this time, our "middleman" - JDBC, through this blog, we can let readers know how to realize ...