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

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

[JavaScript] base conversion & bit operation, what do you know?

Preface Base and bit operations are rarely touched in general code, but this does not mean that we can not learn it. As a programmer, these are the basics. If you haven't learned this knowledge, don't panic. The next knowledge won't be very difficult. In this article, you will learn: Binary conversion Bitwise operator Javascript base conversio ...

Posted by pinochio on Sat, 22 Feb 2020 09:46:22 +0100

3. Querying, adding, deleting and modifying

Article directory First, query 1. Basic query (1) Basic usage (2) Filter data WHERE (3) Sort ORDER BY (4) Character matching query LIKE (5) Query result does not repeat DISTINCT (6) GROUP BY (7) LIMIT query results LIMIT 2. Querying with collection functions (1) COUNT() the total number of rows i ...

Posted by lkq on Fri, 21 Feb 2020 14:23:26 +0100

What has HashMap JDK changed since 1.8?

Recommend a video resource of Gupao College: link: https://pan.baidu.com/s/1SmSzrmfgbm6XgKZO7utKWg Password: e54x First, I will answer the questions that students didn't add in the previous release "be careful when using HashMap". I'd better say how HashMap solves the problem of dead cycle in JDK8. The link list part corresponds to t ...

Posted by zampu on Thu, 20 Feb 2020 09:17:21 +0100

Through Source Code Optimization: How many options do you know for String string performance optimization?

Recommended reading: Ali Liang Jing on both sides: design mode + cache + Spring + virtual machine + MySQL + middleware + concurrency and other problems, all solved Alibaba bytes jump those big factories must ask HTTP how to learn?I suggest you read this article! Ant, byte, PDD social face-to-face via Java post (Distributed + Thread Security + ...

Posted by barrylee on Wed, 19 Feb 2020 19:06:40 +0100

Hans 123 breakthrough strategy in days

Preface HANS123 strategy was first used in the foreign exchange market. Its trading mode is relatively simple and belongs to the trend breakthrough system. This trading mode can enter the market at the first time when the trend is formed, so it is favored by many traders. So far, HANS123 has expanded many versions. Today, we will understand HA ...

Posted by Stille on Wed, 19 Feb 2020 11:06:08 +0100

# IT Star is not a Dream #Illustration of the core source implementation of the kubernetes Scheduler SchedulingQueue

The chedulingQueue is a pair of pod storage in the kubernetes scheduler responsible for scheduling. Scheduler uses SchedulingQueue to obtain pods waiting to be scheduled in the current system. This paper mainly discusses the design and implementation of SchedulingQueue, and explores its internal implementation and underlying source code. This ...

Posted by PHPFEEDER on Tue, 18 Feb 2020 18:20:15 +0100

[PTA] basic programming problem set programming part

Article directory 7-1 cm to FT in (15 points) 7-2 and then what time (15 points) 7-3 three digits in reverse order (10 points) 7-4 BCD decryption (10 points) 7-5 table output (5 points) 7-6 mixed type data format input (5 points) 7-7 12-24 hour system (15 points) 7-8 overspeed judgment (10 points) 7- ...

Posted by plautzer on Mon, 17 Feb 2020 11:54:03 +0100

Chapter 4: data analysis with python

This chapter focuses on the basics of NumPy. Because NumPy provides a very easy-to-use C language API, the data can be passed to the external class library written in the underlying language, and then the external class library will return the calculation results in the way of NumPy array. This feature ...

Posted by sun373 on Mon, 17 Feb 2020 10:52:15 +0100