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recommendation system is currently the most popular technical field, it is the use of E-commerce site to provide customers with merchandise information and advice to help users decide what products should be purchased, simulation sales staff to help customers complete the purchase process. A good personalized recommendation system not only can provide users with personalized service, but also can respond to the user's personalized needs in real time, and can provide the recommended commodity pr

Poor memory: 23-database transactions (1), 23- Database Transaction refers to a series of operations performed as a single logical unit of work, either completely or completely. Transaction Processing ensures that data-oriented resources are not updated permanently unless all operations in the transaction unit are successfully completed. By combining a set of re

There are too many design patterns in the garden. Recently I have also learned the design patterns and sorted out some codes I have practiced and wrote them. net Design Pattern learning notes to give yourself a deeper understanding of the design pattern. I remember when Jin Yong's novels taught me how to make a jump, he said that the general outline of the solitary nine swords is no trick to win, but in fact there is also such a general outline in the design model, that is? Identify the aspects

The tcpdump command is used to crawl network packets, which can print header information for all packets that pass through the network interface, or you can use the-w option to save the packet to a file for later analysis. Common usage:Tcpdump-nn-i ENS33---> Crawl packets that pass through the NIC Ens33Tcpdump-nn Port 80-i Ens33---> Crawl 80-Port packetsTcpdump-nn not port, and host 192.168.1.100---> Crawl non 22 ports and packets from IP 192.168

/nullecho "User $user is added."FiDone ########### #userdel. Sh #!/bin/bashuserlist=$ (Cat user.list) For user in $userlistDoUserdel-r $user 2>>/dev/nullIf [$? = 0]Thenecho "The user $user is deleted!"FiDone Optimization: #usera dd.sh #!/bin/bashuserlist=$ (Cat user.list) For user in $userlistDouser_a=$ (grep-w "$user"/etc/passwd | awk-f: ' {print $} ')If# [$user _a = $user][! $user _a-z] [$user _a = $user]# to determine whether user_a are empty, no

screen to view and then print, then the output to the computer screen content to print, rather than to get the latest data from the database to print.(4) generate Phantom dataT1 after some records have been read from the database according to certain criteria, T2 deleted some of the records, and when T1 again reads the data in the same condition, some records ar

Common commands to use the French side:1. CD:CD dir: Switch the working directory to the DIR directoryCD: Switch to the user login directoryCD-: Switch to the top level directory (two directories switch to each other)CD ~: Switch to home directoryCD ~username: Switch to the specified user home directory for root users only2. PWD:-l:shell problem correction occurs-P: Print out a real physical directory (like

Algorithm increases c++_ch02_04 time limit: 1.0s memory limit: 256.0MBThe problem description outputs the prime number between the 1~100 and displays it. Note that 1 is not a prime number. Output format outputs a prime number per line.23...97 Note: Primes are also called prime numbers.1#include 2#include 3 intMain () {