when does mysql need to create an associated table? such as whether it is appropriate for mysql to use an associated table or to put associated fields in the table, the current design is as follows: 1. Article classification table cate 2. Articl...
without moving anything, I updated the data cache and template cache, and then set some filter words, and then I couldn t read some posts. It s useless for me to delete the filter words, but I can read them when I move to another section. I don t know...
ALTER TABLE `goods_sku` ADD `member_price` int(11) unsigned NOT NULL DEFAULT 0 COMMENT AFTER `price`; Why prompt: 1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax...
such as the question: 0001 strings are stored in the database, how to perform the four operations of integers? ...
in the implementation of panic buying second kill function under high concurrency, I have a question, that is, the problem of data storage, when to store it. idea: 1. Judging that he snapped up successfully, he immediately wrote the generated order da...
In the query back to the table in MySQL, my understanding is that the secondary index cannot directly query the data of all columns, so after querying the clustered index through the secondary index, and then querying the desired data, this process of q...
suppose there is a compound index index_abcd, and the query statement where a = " " and b = " " and c > " " and d = " " at this time c > " " is invalid. How to optimize ?...
seniors, I want to splice the existing fields and fill them in the new fields, such as original table < table > < thead > < tr > < th > id < th > < th > name < th > < th > date < th > < th > record_id < th > < tr > < thead > < tbody > < tr...
recently, I m going to take relational algebra; that is, database principles; my first contact is an abstract sql statement (I don t know if that s right). now I d like to ask, what kind of database should the relational algebra of this way of writ...
recently I am doing a mall type DEMO, like JD.com Taobao and so on. For example, in the commodity details page, in addition to some relatively fixed fields in the head, such as product name, price, profile, and so on, there are also commodity details. T...
is the rollback of the transaction a failure of sql execution or a success of sql execution, but will be rolled back if the number of rows affected by additions, deletions and changes is 0? ...
reference article: Innodb lock mechanism: Next-Key Lock talk about-jyzhou-blog Park Why should Next-Key Lock be designed as a left open and right closed interval? Can t be designed as a gap lock? Why is right closed? ask the boss to answer. < ...
recently installed mysql on linux and searched the Internet for some installation blogs, which are difficult to understand. blog address is as follows: https: blog.csdn.net qq_1623... Question1: what do the following two commands mean respectively?...
rule (the result of formula calculation is the ranking of topic heat): : I would like to ask how such a requirement can reduce the consumption of server performance, can you tell me about the solution? ...
the demand is to query the book browsing data of the last 100 days, and sort the first 23 searches according to the id grouping of browsed books . The statement is: SELECT ip_times.query, books.name,books.cover, COUNT (books.id) AS VALUE FROM ip_time...
specific error is -sharp1193 - Unknown system variable binlog_checksum find out that binlog_checksum only appears in the version above mysql5.6.2 and binlog_checksum=none when it is lower than the following version, but when querying, MYSQL indic...
question: personal calendar, is there one table per user or one table for all users, or is there any other way? my idea: each user has a table with the account number as the table name. When querying, you can find his schedule information according to...
I installed mysql inside docker and can be used in mac. Host is 127.0.0.1 after I put my node application on docker using docker s build command, host reported the following error whether it was 127.0.0.1 or 0.0.0.0 connect ECONNREFUSED 0.0.0...
there are two table-building schemes that I have come up with: first: order_id order id shop_id merchant id goods_id goods id . this way is to write all kinds of id in the order table and associate them when needed. second: order_id order id s...
there are three class1,class2,class3 tables that represent three different classes. The structure of the table is the same, with two fields, name and birthday, indicating the student s name and date of birth, respectively. class1 data: name birth...
D:Vue-Projectportdistancenode_modulesescape-string-regexp:1 (function (exports, require, module, _ _ filename, _ _ dirname) {_ escape-string-regexp@1.0.5@escape-string-regexp ...
https: yuque.com cx5tg dsts7 mid4h I initially thought of the corresponding team (cx5tg) , knowledge base (dsts7) , and the random string of document (mid4h) matched through : teamName :baseName :docName. turns out it s not. The reason comes f...
I have a d3.js and do some operations through var svg = d3.selectall () xxxxx; then this.svg = svg finds that there are not many methods in svg in this.svg, but if there are these methods in this.svg after this.svg.__proto__ = svg.__proto__, I want to kn...
ORM Model Tokens has a field that is the creation time, as follows: create_time = db.Column(db.DateTime, nullable=False, default=datetime.now) Screenshot in the database: stackoverflowcast: db.cast(t.create_time, db.DATE)print: alone prin...
topic description is there any difference between the two writing methods that deal with the above methods without binding this? sources of topics and their own ideas I saw this way of writing when I used the arrow function of es6. I tried it seve...