Spark - upgraded data source JDBC 2
In the data source of spark, only Append, Overwrite, ErrorIfExists, Ignore are supported. But almost all of our online businesses need the upsert function, that is, the existing data must not be overwritten. In mysql, we use: ON DUPLICATE KEY UPDATE. Is there such an implementation? Official: sorry, no, dounine: I have it. You can ...
Posted by smordue on Fri, 22 Nov 2019 07:03:24 -0800
Simple rights management php
Forwarded from https://www.cnblogs.com/shenzikun1314/p/6604867.html#4262295
First, the basic theory to understand is whether the relationship between users, roles and privileges is one-to-many or many-to-many.From this, the table is created.
A user can belong to multiple roles, such as Dunchao.He is Sun Li's husband, his child's father, o ...
Posted by billborric on Thu, 21 Nov 2019 19:49:56 -0800
ORDER BY Causes Poor Index Use
Indexes are often not used as expected in MySQL, and logging the use of an Order by statement today results in an index not being used as expected.
1. Problem phenomena
1.1 SQL statement:
SELECT DISTINCT p.* FROM tb_name p
WHERE 1=1 AND p.createDate >= '2019-10-23' AND p.createDate <= '2019-11-20 24:00:00' AND p.status = '1' AND p.a ...
Posted by phpbeginner on Thu, 21 Nov 2019 18:42:54 -0800
[springboot development monomer web shop] 7. Multiple forms of commodity listing
Review above
Last Section We have implemented the functions of jd-like round-robin advertising and commodity classification, and explained the different injection methods. In this section, we will continue to realize our e-commerce business, the display of commodity information.
requirement analysis
First, before we start coding this section, l ...
Posted by webent on Thu, 21 Nov 2019 16:43:50 -0800
PostgreSQL spatial aggregation performance - administrative area, electronic fence spatial aggregation - time, space thermal map
Label
PostgreSQL, spatial aggregation, spatial heat map, administrative region, electronic fence
background
For a certain time interval (or other conditions), how many objects (space point information) appear in some fences and administrative areas (polygon information), and render these polygons by color depth.
for example
Example
1. Are ...
Posted by ZephyrWest on Thu, 21 Nov 2019 14:12:51 -0800
PostgreSQL pipelinedb flow calculation plug-in - IoT application - real time trajectory aggregation
Label
PostgreSQL, IOT, track aggregation, pipelinedb, flow calculation, real-time aggregation
background
IoT scenes, Internet of vehicles scenes, shared bicycle scenes, human behavior sites, etc. the terminal reports isolated sites in real time. We need to supplement them into tracks.
For example, sharing bicycles, placing orders, unlocking, ...
Posted by haku87 on Thu, 21 Nov 2019 10:23:50 -0800
python: front end (HTML) + back end (Django) + database (MySQL)
1. Create an html file for a simple web page registration demo
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>register</title>
</head>
<body><!--Form field action Used to submit acquired to background address-->
<form action="save" method="get"> ...
Posted by curtis_b on Thu, 21 Nov 2019 07:45:04 -0800
python Foundation (36):pymysql module
1. pymysql module
Before using pymysql module, you need to learn database MySQL: MySQL Foundation.
1.1 download and use of pymysql
After reading the MySQL foundation, we all operate the database through mysql, the command-line client tool of MySQL. How to operate the database in the python program? This uses the pymysql module, which is essent ...
Posted by gazever on Thu, 21 Nov 2019 02:46:11 -0800
Online code editor - codeMirror
Explain
codeMirror is a very powerful code editing plug-in, which provides a very rich API. Recently, this plug-in has been used in the project to make a record.
Official website
github address
install
download the installation package directly on github or clone
npm installation
npm install --save codemirror
Introduce
*Manual introduc ...
Posted by RottenBananas on Wed, 20 Nov 2019 13:49:07 -0800
Detailed JDBC implementation process (add, delete, modify and check)
I. create a table in the database
In this example, MySQL database management system is used. In order to facilitate the operation, Navicat Premium, a graphical interface, is used to operate mysql. The following is the table creation statement:
use test;//Using the test database
create table user_info(//Create a table in the ...
Posted by ntg on Wed, 20 Nov 2019 09:26:43 -0800