MySql must know and be able to read notes

Chapter 7 data filtering Combine WHERE clause AND operator SELECT prod_price,prod_name FROM products WHERE vend_id = 1003 AND prod_price <=10; OR operator SELECT prod_price,prod_name FROM products WHERE vend_id = 1003 OR prod_price <=10; Calculator counts SELECT prod_price,prod_name, ...

Posted by gckmac on Sun, 23 Feb 2020 13:32:22 +0100

Python Dictionary (dict) and list (list) and array (nbarray) details

  Catalog   I. dictionary Declaring dictionary Empty dictionary declaration method Common declaration method (key: value = 1:1) Add a new key value pair to the dictionary Dictionary format Traversal of dictionaries Common loop traversal and output the value of the corresponding key Travers ...

Posted by charlie2869 on Sun, 23 Feb 2020 12:32:42 +0100

How to write multiple if judgments gracefully

Preface In daily projects, we often use if to judge, but in multi-level projects, you will find that the code is cumbersome demand Now there are four products, namely mobile phones, computers, televisions and game consoles. Of course, the prices of each product are different if judgement To see such a r ...

Posted by Daniel0 on Sun, 23 Feb 2020 11:01:48 +0100

Insights into applets

Insights into applets Counter war What is applet Small program is an application that can be used without downloading and installation. It realizes the dream of "within reach" of the application. Users can scan or search the application to open it. It also embodies the concept of "go ...

Posted by mwd2005 on Sun, 23 Feb 2020 10:29:42 +0100

Dictionary public method

Dictionary public method Dictionary introduction Think about it: If there is a list nameList = ['xiaoZhang', 'xiaoWang', 'xiaoLi']; You need to write the name "xiaoWang" wrong. Modify it by code: nameList[1] = 'xiaoxiaoWang' If the order of the list changes, as follows nameList = ['xiaoW ...

Posted by thepreacher on Sun, 23 Feb 2020 10:01:49 +0100

Basic operation of Hive

Article directory 4, DDL data definition 4.1 create database 4.2 query database 4.3 modify database 4.4 delete database 4.5 create table 4.6 zoning table 4.7 modification table 5, DML data operation 5.1 data import 5.2 data export 5.3 clear data in the table (Truncate) Six, query 6.1 basic query ...

Posted by PyroX on Sun, 23 Feb 2020 09:38:46 +0100

MySQL basic: MySQL data operation

Catalog Add record Update record Delete record Query record WHERE condition GROUP BY multi-table query Create foreign keys Joint query Common mathematical functions of MySQL Common string functions of MySQL Date functions commonly used in MySQL Other common functions Add record # grammar INSERT [I ...

Posted by juancuca on Sun, 23 Feb 2020 08:59:29 +0100

Circular list (one way + two way)

1, One way circular list 1. One way circular list details In fact, a unidirectional circular list is a pointer to the head node of the end node. Generally, the end node of the list points to null. When adding a node, the tail situation is the same as the normal situation, and no special processing i ...

Posted by ghqwerty on Sun, 23 Feb 2020 07:46:35 +0100

Using ffmpeg to split the video file into several ppm pictures

Using ffmpeg to split the video file into several ppm pictures thinking Get path - > unpack - > get video stream information - > decode - > YUV420 to RGB - > store in ppm format. Pseudo code step1. Registration Step 2. Open audio and video files Step 3. Get audio and video stream st ...

Posted by iBlizz on Sun, 23 Feb 2020 05:29:45 +0100

Docker's Custom Mirror Upload Aliyun

Introduction to Alpine Linux 1.Alpine Linux is a lightweight Linux distribution. It is different from the usual Linux distribution (centos, Ubuntu), Alpine uses musl libc and BusyBox reduces system size and runtime resource consumption. 2.Alpine Linux provides its own package management tool ...

Posted by lanjoky on Sun, 23 Feb 2020 05:29:38 +0100