The first chapter is the basic syntax specification of SQL
1.sql is not case sensitive, but it is customary for keywords, system reserved words, function names to be uppercase, and table and column names to be lowercase
2.sql uses space or carriage return to separate each word. It is customary for ...
Posted on Mon, 29 Jun 2020 03:51:57 -0400 by weevil
Before MySQL 8.0, it was quite painful to do data ranking statistics, because there was no window function like Oracle, SQL SERVER, PostgreSQL and other databases. However, with the addition of window functions in MySQL 8.0, it is no longer a problem for this kind of statistics. This paper introduces MySQL window functions with common sorting e ...
Posted on Sat, 27 Jun 2020 03:42:25 -0400 by always_confused
Author: Zhao Liming
Aikesheng, a member of MySQL DBA team, Oracle 10g OCM, MySQL 5.7 OCP, is good at database performance problem diagnosis, transaction and lock problem analysis, and is responsible for dealing with the problems in the daily operation and maintenance of customer MySQL and our company's self-developed DMP platform, and is very ...
Posted on Tue, 23 Jun 2020 06:07:02 -0400 by ultraviolet_998
@Java null pointer exception
Exception in thread "main" java.lang.NullPointerException
In the previous writing experiment, we encountered a java null pointer exception problem. After multiple queries of data, China and Vietnam solved the exception, so we decided to record the solution of this exception. ...
Posted on Sun, 14 Jun 2020 05:25:00 -0400 by Crys
Some time ago, someone in the QQ group was confused about "I update d the data in this row of table (0,4), looked at the page data of the index, and found that the index always points to (0,4), and I can't find the data by querying the business table with ctid='(0,4)"; then I made the vacuum of the ...
Posted on Tue, 09 Jun 2020 23:11:28 -0400 by niki
This paper is learning notes, mainly used to record my learning process. Part of the content for reprint!!!!
1, What are the reasons for Mysql's Master-Slave synchronous replication, read-write separation?
For some current large-scale websites, only one database server is not enough to handle a lar ...
Posted on Sun, 07 Jun 2020 23:59:55 -0400 by koughman
KVM version: QEMU emulator version 2.5.0 (Debian 1:2.5+dfsg-5ubuntu10.16)
Virtual Machine: Ubuntu-Server 16.04.3 LTS
Install FTP, File Transfer in ubuntu Server
The network is connected.Install openssh server
$sudo apt-get install openssh-server
$sudo apt-get install openssh-sftp-server
Posted on Sun, 07 Jun 2020 12:48:28 -0400 by Profector
ORM Conceptual Analysis
First, comb out the concept of ORM. The spelling of ORM is Object Relation Mapping (Object Relation Mapping), where Object is the object in Object-Oriented Language. This paper uses c# language, so it is a.net object. Relation Mapping is a relationship mapping, which refers to the relationship mapping between.net object ...
Posted on Wed, 03 Jun 2020 22:04:41 -0400 by Major Tom
1. What is PL/SQL?
PL/SQL (Procedure Language/SQL) is a procedural extension of Oracle to SQL language. It refers to the addition of process processing statements (such as branch / condition, loop, variable, type, etc.) in SQL command language, which makes SQL language have process processing ability. By combining the data manipulatio ...
Posted on Wed, 03 Jun 2020 13:02:44 -0400 by wkoneal
1. Linux 6 + emcc188.8.131.52 installation environment introduction
l this set of environment is based on rhel6.10 + Oracle 184.108.40.206 single node database
L java development kit (JDK)220.127.116.11.0
L Oracle WebLogic Server 11g version 1 (10.3.6)
Orac l e Management Office 12c 5th Edition (18.104.22.168)
1.1 check users, groups
$ more /etc/oraInst.loc
Posted on Tue, 02 Jun 2020 12:54:47 -0400 by HavokDelta6