such as the question: if you want to randomly query multiple pieces of data, which cannot be repeated each time, how to achieve it?
such as the question: if you want to randomly query multiple pieces of data, which cannot be repeated each time, how to achieve it?
you can add a field to the database table to mark it;
, or put the checked data primary key into the set of redis, and click Filter
mybatis+mysql for java projects int batchAmount = 20000; for (int startIndex = 0; startIndex < size; startIndex += batchAmount) { int endIndex = startIndex + batchAmount; endIndex = (endIndex &...
recently, when I was writing a node project, I found that it was troublesome to write a bunch of sql statements when connecting to mysql with node.js. I went to npm s official website to search for nothing, so I would like to ask if there is a similar f...
Mysql create stored procedure: create procedure s_add(in a int, in b int, out sum int) begin set sum = a + b; end After , this is the Java code package ch04.servlet; import java.io.IOException; import java.io.PrintWriter; import java.sql.Ca...
if in the business layer, within a transaction, there is an if judgment read in the database first, judge according to the result if else, and then read write to the database and there are if else statements within the mysql database if you are i...
what is stored in the database is the html code, which is mainly a piece of div content, including the style, does not contain the body and other tags, and the label is strict in opening and closing. If I want to query the keyword "class " now, if I us...
at present, there is a demand. Alipay or Wechat can be used to pay for second-kill merchandise activities, but the problem is that the demand must be paid before deducting inventory, and placing an order does not reduce inventory. In other words, when A...
this semester, the teacher gave a project, which is to design a push system. The main function is to realize the function that the server pushes data to the mobile or PC, and the mobile or PC can feedback the data. Because I am a mechanical student, I d...
mysql no compatible servers were found.you ll need to cancel this wizard and insta cannot check.. either ...
for stand-alone service, the primary key ID is a long integer, which needs to be non-continuous. For example, self-increment cannot be implemented because it is continuous. I thought of using System.nanoTime () to do ID, because I haven t practiced it...
how should a like collection system design a data table? I intend to add an array to the user table, put the id of the like content in it, cancel the like, and then remove the id from the array . find a better way ...
problem description: a blog system is being developed that needs to achieve the top of an article, and then the foreground will display the article (or more than one) at the top. What I want is to add a new field to determine whether it is a top article...
there is such a requirement: user login module, does not support the choice of login method, only a text input box, while supporting: QQ number, mobile number, e-mail, nickname, ID card, etc. (if the user filled in the values of these five fields) any f...
1: { name: A , age: 10 } 2: [{ id:1, name: A , 1name book: xxx }, { id:2, name: A , book: xxx }] name A book are all stored in Table 2. How to deal with a table structure like this? ...
1. What kind of record is used in the card game record? I think MongoDB would be better, wouldn t it? 2. Is the logic of playing cards in any language? Is it okay to develop with php ? 3. are the rules of the game and card logic quite difficult? ...
for example, the function of backing up the database is encountered in the project, but the database itself is not installed on the machine where the project is running. Is there any good class library you can recommend? (^ ^) attachment: it is not f...
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as shown in the figure, Table 1 is associated with Table 2. How to click submit and save the two tables together ...
mysql database Save the code as follows: : ...
as shown in the figure, if you write x.from_unixtime (xxx,xxx) directly with js, you will report an error directly. how should the value of this object be read? Hurry! ...
bulkCreate (records, [options])-> Promise. < Array. < Instance > > after setting the options.ignoreDuplicates option, instances of records array records will be returned regardless of whether they are created or ignored. How to get only the affected row...