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 ...
Tools: CMD sqlplus
Content: basic table operation, plsql programming (branch structure, loop, judgment, etc.)
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.
Added by ianitm on Mon, 30 Mar 2020 19:37:27 +0300
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
1. Connect to the database
mysql> show create database shop \G;
*************************** 1. row ***************************
Create Database: CREA ...
Added by jvanv8 on Fri, 27 Mar 2020 17:03:39 +0200
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 $$
select hstore( ...
Added by m4rw3r on Tue, 24 Mar 2020 17:11:38 +0200
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
First, create a PlaceController controller ...
Added by zab329 on Mon, 23 Mar 2020 11:54:51 +0200
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 used by friend company Mysql connection pool, the application accesses Mysql as domain name, which is configured as follows:
All middleware access is through th ...
Added by navtheace on Sun, 15 Mar 2020 04:17:09 +0200
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
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1. o ...
Added by Superian on Thu, 12 Mar 2020 11:42:09 +0200
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
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