orchestration lessons

the where clause having . You can use exist and not exist instead of In and not. You can use table links instead of exist. Having can be replaced by where , if not replaced, can be handled in two steps. Example SELECT * from ORDERS WHERE customer_name not in (SELECT customer_name from CUSTOMER) Optimized SELECT * from ORDERS WHERE customer_name not exist (SELECT customer_name from CUSTOMER) 7.2 do not declare numbers in character format, you want to declare character values in numeri

database version select version ();• View database status show status;(data not all shown)• View each parameter show variables; Show variables like ' max_connect% ';Show variables;(Too many parameters)• Modify parameter set global max_connect_errors=1000;If you want to permanently take effect, you need to exit to SHELL,VIM/ETC/MY.CNF, define max_connect_errors=1000;• View queue show processlist; Show full processlist;If there are errors, please correct, learn from each other and progress togeth

rows affected (0.01 sec)• Completely delete the database:Drop database db1;mysql> drop Database db1; Query OK, 1 row affected (0.01 sec) 13.6 MySQL Database backup recovery• Backup library:Mysqldump-u User name-p password Database > backup data file path[Email protected] ~]# mysqldump-uroot-p123456 mysql >/tmp/mysql.sql(Too much data is not listed)• Recovery library:Mysql-u User name-p password Database [Email protected] ~]# mysql-uroot-p123456 MYSQL2 • Backup table:Mysqldump-u Use

the WHERE clause is used in the inch , not in , or or having . can use exist and the Not exist Replace inch and the not in . You can use table links instead exist . Having can be replaced by where , if not replaced, can be handled in two steps. ExampleSELECT * from ORDERS WHERE customer_name not in(SELECT customer_name from CUSTOMER)Optimized SELECT * from ORDERS WHERE customer_name not exist(SELECT customer_name from CUSTOMER)7.2 do not declare numbers in character format, you want to dec

10.28 Rsync Tools IntroductionThe file Synchronization tool rsync, can achieve incremental copy, CP is direct coverage, low efficiency;Install rsync, #yum-y install rsync;Rsync Common methods,Copy the passwd file to the/tmp directory, rename it to 1.txt, and the command to #rsync-av/etc/passwd/tmp/1.txt-V visualization;Remote copy, command for #rsync-av/etc/passwd [email protected]:/tmp/1.txt; then enter the password;10.29/10.30 rsync Common Options10.31 rsync sync via ssh-e Specifies the port,

14 weeks four sessions (May 14)16.1 Tomcat Introduction16.2 Installing the JDK16.3 Installing Tomcat16.1 Tomcat Introduction16.2 Installing the JDKOpen the download URL.Click jdk=8u144-linux-x64.tar.gz, downloadUpload to LinuxCtrl+f Open XftpPut the downloaded file in the root directoryXftp is an SSH-based port that does not require FTP to be opened.CopyAt the bottom, pasteCheck to see if the installation is successful, the following results appear, stating that there is no problem, the command

();-------------------------------------------------------------------curl-x127.0.0.1:80 test.com/upload/3.php //Can not parse, directly to the source code (written content) display/usr/local/nginx/sbin/nginx-t/usr/local/nginx/sbin/nginx-s Reloadcurl-x127.0.0.1:80 test.com/upload/3.php //Normal parsingTail/usr/local/nginx/logs/error.log//View error log12.16 Nginx AgentCd/usr/local/nginx/conf/vhostVim proxy.conf//Add the following:-----------------------------------------------------------------

Tags: Linux notes12 weeks three sessions (April 25)12.10 Nginx Access Log12.11 Nginx Log Cutting12.12 static files do not log logs and expire time12.10 Nginx Access LogThe format of the configuration file is in the main configuration file.Search for log to find the following paragraph, which is used to define the format.Public network IP, in Baidu, search IP, view.Defining Access Log pathsOpen FileUnder}, add a row to read as follows:12.11 Nginx Log CuttingEdit FileAdd the following contentProce

= ' date-d '-1 day +%y%m%d '//similar to 20180427, yesterday's date, today 28thLogdir= "/data/logs"Nginx_pid= "/usr/local/nginx/logs/nginx.pid"CD $logdirFor log in ' ls *.log 'DoMV $log $log-$dDone/bin/kill-hup ' Cat $nginx _pid '--------------------------------------------------------------------------------------Add Task Schedule #crontab-e//write the following:0 0 * * */bin/bash/usr/local/sbin/nginx_logrotate.sh//Daily 0 o'clock in the morning execution12.12 static files do not log logs and e

of memory requirements will B,PB,RB have? Either pointer or reference requires only one word space (32 is 4-bytes on the machine). Bear object needs 24bytes, that is, Zooanimal's bytes plus the 8 bytes that bear brings.Well, suppose our bear object is placed at address 1000, what is the difference between a bear pointer and a zooanimal pointer?Bear B;Zooanimal *pz = b;Bear *PB = b;Each of them points to the first byte of a Bear object. The difference is that PB covers an address that contains t

Lessons learned by beginners When I first went to college to study C language, I suffered a lot of losses when downloading the IDE and compiler. Although it was not a very profound problem, I decided to share it. Some senior recommended me Clion as IDE, and some teachers recommended my code blocks as IDE. I downloaded two files at the same time, installed them according to the Baidu tutorial, and edited them, but finally found that the program could n

monitoring file changes in the folder4. Import data into HDFs5, the instance monitors the change of the folder file and imports the data into HDFs3rd topic: AdvancedHadoop System Management (ability to master MapReduce internal operations and implementation details and transform MapReduce)1. Security mode for Hadoop2. System Monitoring3. System Maintenance4. Appoint nodes and contact nodes5. System upgrade6, more system management tools in combat7. Best Practices in System management4th topic:

About Whistling Android Videos:The most important feature of this video is practical, which should be said, which should not be said, I have done careful consideration. There is no imaginary head eight brain, pedantic, also useless long things. Everything is simple and clear.Today is the first lesson:The main contents are:1. Installing the JDK2. Configure Environment variables3. Download the Android SDK4. Create a new AVD5. Run the first projectVideo playback Address: Click the Open linkThe firs

a beautiful arch-shaped canal in front of Taihe square, and then turn to the North Stream via wenyuan pavilion, in the west of the kaikku outflow of the palace. The inner river stretched for more than 2000 meters in the palace. There were 21 bridges on the river, large and small, and there were more than 10 culverts. In addition to practical functions such as excretion of rainwater, facilitating water intake and fire fighting in the palace, nejin River is also a factor that cannot be ignored. M

Lessons learned from a salary negotiation Lai Yonghao (http://laiyonghao.com) Note: This is an article written at the end of 2008. On April 9, (post-paid note), I participated in a salary negotiation and got into the other party's flying knife. I was very embarrassed. Finally, I had to stick to the decision, so that the whole city would not be exhausted. This "lesson" is recorded in the close-up. One is to watch yourself, and the other is to help ot

Author: Regina Brett To celebrate my getting older, I wrote 45 lessons that I taught me in my life. This is the most challenging column I have ever written. I am about to be 90 years old in August, so I will present this column again: 1. Life is unfair, but it is still good.2. When you are skeptical, take a small step for the future.3. Life is too short to waste time hati

The C programming time on the Linux platform for beginners is not long. This time, a business project needs to use the queue. I studied and compared the related products on the market, in general, it is not too complicated or the performance cannot meet the requirements. Therefore, I decided to write one by myself. This is the second time that C is fully implemented by itself. In the past, it was changed to the next open-source software. Generally, the performance of software under Linux is acce

. Weakness is not weakness. Let others be as open and humble as you are. If someone points out what you need and how you feel it makes you feel uncomfortable, it is more about telling you your situation. Rough edge position Someone else will spy on your boundary. In this case, you know when to leave and when to stick to it, and you have already won the halftime. Sometimes some people will play too much. In this case, they should express their positions and make them brake quickly. Otherwise

temporary files, but it does not have the permission. Therefore, login to> record fails, and the root user does not have this problem. Run sudo chmod 1777/tmp Log on again and log on successfully. Lessons learned: The main reason for the modification of/tmp directory permissions, UID and GID is that the no_root_squash option is set in the/etc/exports file. According to the description in "laruence's private house dish: No_root_squash: The user who l

"first chicken, first egg", entangled in it. Users, relationships, and strong resource and topic production capabilities need to be developed in the early stage. Here are some suggestions for colleagues who are interested in social apps:If you don't have a lot of resources, don't invest in social apps. This is a money-burning thing. Obtain user resources, which can be diverted from other places. For example, the first public account to attract target users. Or, you can develop the correspondin