MySQL database learning notes (3)

Functions in MySQL Functions in MySQL include character function, numeric operator and function, comparison operator and function, date time function, information function, aggregate function, encryption function, etc. 1. Character function //For example, when you need to output last name and first name togethe ...

Added by Yaak on Thu, 02 Apr 2020 02:25:26 +0300

Learning: simple programming of plsql for Oracle Database

Tools: CMD sqlplus Content: basic table operation, plsql programming (branch structure, loop, judgment, etc.) Account: scott preparation in advance Tips for using cmd Because the author uses sqlplus and enters in the cmd environment. It's not easy to edit the text in cmd environment, so I'll give you some tips. A ...

Added by ianitm on Mon, 30 Mar 2020 19:37:27 +0300

Details of php pdo object usage: connecting database and exec method

To use pdo, you need to open the pdo extension first. I have opened the pdo extension of mysql here ghostwu@dev:~$ php -m | grep pdo pdo_mysql ghostwu@dev:~$ 1. Connect to the database mysql> show create database shop \G; *************************** 1. row *************************** Database: shop Create Database: CREA ...

Added by jvanv8 on Fri, 27 Mar 2020 17:03:39 +0200

Table based ddl (alter table) audit of Postgresql

If you want to record the user table modified and defined by DDL, set the default value, and so on, you can use event triggers to achieve this purpose. Examples are as follows: testdb=# create extension hstore; testdb=# create or replace function ef_alter() returns event_trigger as $$ declare rec hstore; begin select hstore( ...

Added by m4rw3r on Tue, 24 Mar 2020 17:11:38 +0200

Laravel Model Association, association query, preload use instance

Data tables are usually associated with each other, and it is usually easier to use multi table associated query, which is more convenient and simple for more complex model associated query using laravel, Chinese document , take two tables of provinces and cities as an example Preliminary preparation: First, create a PlaceController controller ...

Added by zab329 on Mon, 23 Mar 2020 11:54:51 +0200

Builder Mode of Creative Mode

1 Overview As we said earlier Factory Mode and Abstract Factory Mode , let's talk about the builder model. The builder mode is also a very common creation mode. The two factory modes mentioned earlier hide the properties and construction details of a class, while the builder mode exposes the properties of a class appropriately through the Build ...

Added by g-force2k2 on Sun, 22 Mar 2020 09:04:09 +0200

BoneCP Connection Pool Reconnection Mechanism Analysis

1. Background BoneCP used by friend company Mysql connection pool, the application accesses Mysql as domain name, which is configured as follows:   jdbc:mysql://order.mysql.xx.cn:3306/order?useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true All middleware access is through th ...

Added by navtheace on Sun, 15 Mar 2020 04:17:09 +0200

Analysis of distributed DBLE LOAD DATA function implementation

Author: Lu Lu Those who love technology and are willing to share are mainly engaged in the research of database related technology. Source: original contribution *Aikesheng is produced by the open source community. The original content cannot be used without authorization. Please contact the editor for reprint and indicate the source. 1. o ...

Added by Superian on Thu, 12 Mar 2020 11:42:09 +0200

Gausdb 100 stand alone upgrade Guide

The purpose of this article is to introduce how to upgrade GaussDB stand-alone database from 1.0.0 to 1.0.2. Single machine supports automatic upgrade of small version and binary upgrade. For automatic upgrade, only one upgrade command needs to be executed on the node. 1. Upload package and decompress Upload the following two packages to the s ...

Added by suntra on Thu, 12 Mar 2020 11:37:15 +0200

Function index (Generated Column) and SQL optimization in MySQL

There is no function index function of Oracle in MySQL. It is not accurate to call the Generated Column of MySQL as "function index", but it can achieve the same effect as the function index. Some people also call this feature "derived column". What is Generated Column The value of Generated Column is calculated according to ...

Added by bettyatolive on Sun, 08 Mar 2020 11:44:01 +0200