• ## Time series prediction in Statistical Science (Part 2)

Time：2021-12-6

The first two articles introduce several direct prediction methods for time series. This one tells you how to decompose time series and predict data according to the decomposition method. To predict an index, we must first know what factors affect the index. If the leader asked you to estimate the sales volume of next month, […]

• ## Learn the use of statistical extension functions in PHP

Time：2021-9-7

Friends who do statistical related systems must have learned concepts such as normal distribution, variance and standard deviation. In PHP, there are also corresponding extension functions specially developed for these statistical related functions. The stats extension library we are going to learn today is this kind of operation function. Of course, I haven’t done any […]

• ## 50 SQL statements (MySQL version) problems

Time：2021-7-6

————————–Table structure————————– Student (studid, studname, studage, studex) student table Teacher (TID, tname) teacher table course(CId,Cname,C_ TID) curriculum sc(SId,S_ CID, score) ———————————————————- Question 21: query the average score of different courses taught by different teachers from high to low SELECT t.Tname,c.Cname,AVG(sc.Score) AvgScore FROM teacher t,course c,sc WHERE t.TId=c.C_TId AND c.CId=sc.S_CId GROUP BY t.Tname,c.Cname; The answer is […]

• ## Java   Version of student performance management system, with source code!

Time：2021-7-3

preface For students majoring in computer science, they must be very impressed by the course design of student performance management system. Design, computer, coding, report writing, defense and a series of processes, although very simple, but we can also use some of our knowledge. Today, let’s review the following topic, using java se to realize […]

• ## Course design C language student achievement management system

Time：2021-5-9

Student achievement management system Tips: notes should be written are written, suitable for beginners reference.The maximum number of students in a class is not more than 30 (the specific number is input by the keyboard), and the maximum number of examination subjects is not more than 6 (the specific number is input by the keyboard). […]

• ## Load balancing of reverse proxy

Time：2021-4-23

load balancing :As soon as we listen to this word, many of our friends are scared. Our predecessors like to make some words that look very tall, so that future generations can be awed by them. Let’s smooth them out. Load is the burden. Balance is the average score. In this way, it is the […]

• ## DQL query statement

Time：2021-1-19

Sort query*Syntax: order by clause*Order by sort field 1, sort method 1, sort field 2, sort method 2 *Sort by: *ASC: ascending order, default. *Desc: descending order. *Note: *If there are multiple sorting conditions, the second condition will be judged only when the condition values of the current edge are the same. Aggregate function: a […]

• ## Antutou released the Android mid end mobile phone performance list in May 2020, and MediaTek Tianji 1000L ranked first temporarily

Time：2021-1-19

Technical editor: Wang ZhizhiSegmentFault has he reported the official account number: SegmentFault Recently, antinu released the Android mid end mobile phone performance list in May 2020. According to the list, Lianfa Tianji 1000L has become the new generation of mid end performance king, surpassing Kirin, Xiaolong and exynos. Ranking first this month is oppo Reno […]

• ## SQL sort

Time：2020-11-26

Sort 1, 2, 2, 2, 3, 4 with the following function: select row_ Number() over (order by field) from table name; 1、 row_number() Values: 1, 2, 2, 2, 3, 4 Sequence: 1, 2, 3, 4, 5, 6 2、rank() Values: 1, 2, 2, 2, 3, 4 Sequence: 1, 2, 2, 2, 5, 6 3、dense_rank() Values: 1, […]

• ## [SQL interview question 2] MySQL and Oracle Database

Time：2020-7-23

1. If matched, update desc of dictb to corresponding field desc in dicta First create two tables: CREATE TABLE DictA(id1 number, desc1 varchar2(10)); CREATE TABLE DictB(id1 number, desc1 varchar2(10)); Insert into dicta values (1001, ‘fund’); Insert into dicta values (2001, ‘insurance’); Insert into dicta values (3001, ‘securities’); Insert into dicta values (3002, ‘trust’); Insert into […]

• ## Is it feasible for RSI index to judge bitcoin price trend?

Time：2020-6-3

1. Principle of RSI index The relative strength index (RSI) was created by wells wider in June 1978. It is a kind of technical index to judge the internal strength of asset prices and predict the future direction of price changes by calculating the comparison of market buying and selling forces based on the changes […]

• ## Oracle compute time format average

Time：2019-11-3

select to_char((to_date(‘2019-07-01’, ‘yyyy-mm-dd’) + numtodsinterval(avg(begin_time_second), ‘second’)),’hh24:mi:ss’) avg_begin_time,to_char((to_date(‘2019-07-01’, ‘yyyy-mm-dd’) + numtodsinterval(avg(end_time_second), ‘second’)),’hh24:mi:ss’) avg_end_time–2019-07-01 00:00:00 + numtodsinterval (average, ‘seconds’) is converted to date format and then to time character formatfrom (　　select — convert working hours to seconds 　　to_char(a.actontime, ‘hh24’) * 3600 + 　　to_char(a.actontime, ‘mi’) * 60 + 　　to_char(a.actontime, ‘ss’) as begin_time_second,— convert off hours to seconds 　　to_char(a.actofftime, […]