• Detailed explanation of the comparison between partition by and group by


    Today, I understand the difference and connection between partition by and group by. 1. Group by is a grouping function, and partition by is an analysis function (and then sum() is an aggregation function); 2. In the order of execution, The following is the priority of common SQL keywords from > where > group by […]

  • Super chain college online open class: decrypting parallel chain group function live tonight


    Super chain college online open course, recently launched xuberchain V3.7 new function analysis series courses Tonight, I’ll show you the function of parallel chain group More specific demonstration hand in hand teach you to compile group management contract! Quick point live booking link registration~ [guest speaker]: Sun Junyi, senior R & D Engineer of Baidu, […]

  • Group by group statistics and query by a certain period of time (recommended)


    It is required to group the timestamp fields in the log table. The condition of grouping is that the students are divided into one group at one minute interval. The database table looks like this SELECT COUNT(log_id) AS u_count FROM logdb.`log` GROUP BY TIMESTAMP-TIMESTAMP%(1*60) Where timestamp is the database time field. The 1 in brackets […]

  • It’s worth collecting! Quick reference manual of common commands in Linux system


    I have collected and sorted out the daily Linux system commands for your reference only. If you feel that the article seems inconvenient, the migrant worker has also compiled this command into PDF. You can refer to the way at the end of the article to obtain the quick reference manual of common Linux system […]

  • Three methods of deleting duplicate records in Oracle query


    For example, there is a personnel table (Table Name: peosons)If you want to record the name, ID number and address of the three fields exactly the same, Copy codeThe code is as follows: select p1.*   from persons  p1,persons  p2   where p1.id<>p2.id   and  p1.cardid = p2.cardid and p1.pname = p2.pname and p1.address = p2.address The above […]

  • Record of the first day of the establishment of the learning group


    1. The original intention of the study group: Let’s study together and make progress. You can join us voluntarily and quit at any time. Don’t have any mental burden. Open source, open mind, the spirit of sharing, based on the long-term, common growth. The idea comes from: https://segmentfault.com/u/ph… 2. Why to set up a study […]

  • Thoughts on scrum training


    As a graduate student, I worked as an intern for three months in a consulting company in Beijing. At that time, the project in charge adopted agile method for project management, which gave me a rough understanding of agile. Back in school, I’ll hear more or less agile and scrum concepts in class and in […]

  • Group and group administrator in Linux user system


    On groups: valid and initial groups, groups, newgrp Copy code The code is as follows: # /etc/group This file records the correspondence between GID and group name – my / etc / group content is a bit like this: Copy code The code is as follows:   root:x:0:root  bin:x:1:root,bin,daemon  daemon:x:2:root,bin,daemon  sys:x:3:root,bin,adm The colon ‘:’ is also used as the […]

  • Ubuntu group management


    group management stayLinuxIn, each user has a group. So when creating a new user, there is no specified group. How does the group come from. In fact, we do not need to set up a group. When creating a user, a group with the same user name will be created by default, and the user […]

  • Implementation of FISCO bcos flow control


    Source: FISCO BCOS open source community official accountAuthor: Chen Yujie / FISCO bcos core developer 1. Introduction As a distributed system, the blockchain system is faced with a large amount of data burst request scenarios, the skyrocketing requests are easy to cause the blockchain service or interface unavailable, and in serious cases, the whole blockchain […]

  • What is the black technology that makes this steel plant with 120000 employees and 17000 products go smoothly to the cloud?


    Abstract:If you want to make the network environment migrate to the cloud as a whole, is there any service insensitive smooth migration method? Listen to Kyon about the “calm” power of clouds on Hegang. In August 2020, on a normal weekend, five core business systems of HEC’s supply chain were quietly transferred to Huawei cloud. […]

  • SQL: Recursive query in MySQL


    DROP TABLE IF EXISTS `dudept`; CREATE TABLE `dudept` ( `Id` int(11) NOT NULL AUTO_INCREMENT comment ‘ID’, `deptCode` varchar(10) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL comment”, `deptName` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL comment”, `pCode` varchar(10) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL comment”, `ParentId`int(11) not null comment ‘Parent ID’, PRIMARY […]