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see View all indexes in the database db.system.indexes.find () db.system.indexes.find () on the Internet. Why is it so after I type it ...
1. How to decompose (A, B)-> E, (C, D)-> E, A-> C, C-> An into BCNF,? 2, U = (Agraine Brecinct C pyrrhene E) F = {B-> Greco ce-> Breco C-> Areco B-> Dle le C-> D}. Decompose into BCNF? 3. The BCNF decomposition that I understand at present is to fin...
recently, I have been learning distributed architecture. I have basically figured it out. What about the database? the mysql, I ve been using take mysql as an example for example, I now have two databases of server B. According to the load balancer,...
take MySQL as an example, what is the difference (principle and efficiency) between in and exists and between not in and not exists? What about using indexes? Say that not in and < > will not use indexes, won t you? ...
(the mobile version can t upload the picture, go back to make it up tonight) General uid. If the figure above is a string of fixed-length numbers, how is it generated? When storing uid in a database, doesn t it usually start at 1 and then grow itsel...
what do you mean by sub-database and sub-table partitioning of the database? ...
after reading this article (introducing schema in the database) https: www.biaodianfu.com da., it is mentioned that the schema in MySQL is the same as the library. Is this correct? Thank you ....
Database oralce query data based on the following parameters how to query, do you have any ideas? ...
seniors, I have a problem that I can t solve. I hope you can take the time to answer it. I want to print the data from the database through vue-markdown, but after going through it with v-for, I get undefined. Also used v-text instead of {{}} to outp...
for example, go connection mysql, https: github.com jmoiron sqlx is a client that implements official database sql, and an additional driver: https: github.com go-sql-dri. is required to use it. but this is not the case when I connect to mongodb. ...
there is a new requirement that needs to add a field X to the table TABlE_A. Suppose X has values of 0 and 1, but for historical data, the value of this field is NULL,. What do you prefer to do at this time? data revision. Brush over the historical d...
first of all, I found a lot of database design on Baidu, it can be said that there are different opinions! I see an intermediate table is designed like this, commodity ID sku attributes, unit price inventory, see that the intermediate attributes store js...
how do facebook, Weibo comments and comment responses and comment likes be stored? It feels like it takes a lot of effort to use a relational database. ...
for example, the comment table is divided into 100tables and divided according to the userid hash algorithm, so the background management should display the comment list, but cannot jointly query 100tables. How do you do this? ...
I have a company employee mailing list and a new employee mailing list. I need to open an email for new employees. I ve been using excel manually. I want to try to use access to automatically achieve . I need to query the duplicate name and add the nu...
if the data to be saved contains "`, how can it be inserted into the database? A rookie, please give me some advice. ...
because InfluxDB clusters are charged. Now you are ready to use message queuing to solve the normal data Synchronize of the InfluxDB database cluster. But if a database server goes down, and then restart and start, how to recover the data and turn the da...
prepare to develop book reading class app, backend to choose which database can better store book content. In the past, relational databases were used. Experienced people can guide them ....
mongoose What is the reason for ? ...
problem description I want to use redis to do session. Now I set the expiration time to 7 days, but now I can t find redis data for less than one day. Since redis is built by myself, I would like to ask you what might be the problem with redis. the...
now you need to use Samba to get something, but haven t there been security problems before, so I d like to ask which version is the safe version now? My side is Ubuntu 16.04 LTS apt-get version 4.3.11 installed by default ...
import urllib,urllib2,cookielib loginurl= http: 192.168.1.80 login.htm cj = cookielib.CookieJar() opener=urllib2.build_opener(urllib2.HTTPCookieProcessor(cj)) headers = { User-Agent : Mozilla 5.0 (Windows NT 6.1; Win64; x64) AppleWebKit 5...
error: vue.esm.js?efeb:591 [Vue warn]: Invalid prop: type check failed for prop "list ". Expected, got Array. this is the initialization of list ...
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