if MySQL is a few questions about master-slave synchronization 1) can one slave synchronize data from multiple master, or can one slave only work for one master and one master for multiple slave 2) must their database names be the same for master and...
after win10 installs fiddler, click to run the software and flash directly. No big god has ever encountered such a situation. ...
use strict ; module.exports = { up: (queryInterface, Sequelize) => { return queryInterface.createTable( tbl_wechat_user , { id: { allowNull: false, autoIncrement: true, prima...
horizontal subtable can improve the efficiency of the query, but if the order table is divided into 100 tables, I want to query all the orders of a user, how to deal with this? ...
problem description this kind of business is involved in the development. My idea is as follows: polymorphic association is used. This structure is particularly troublesome, relying on code implementation, and requires better solutions. has a course ...
for example, if you do a SQL query of statistical data, the tables come from all directions and have different conditions. If multiple select count are efficiently implemented in a SQL statement, only SQL is considered here. For example, sql is as follo...
SELECT T.[ID] AS ID, A.UserName AS , T. AS , T. AS , W.[ID] AS ID, B.UserName AS , W. AS , W. AS , X.[ID] AS ID, C.UserName AS , X. AS , X. AS FROM ( SELECT MX.[ID], SUM (CONVER...
Test database downloaded on github. Index: explain select: query the scope of the date field of the employees table if you want to query the recruits in a certain period of time, 1. Why interpret the results, using the type field or ALL? What doe...
there are two tables an and a column a_id in bdepartment b that stores table an id as a foreign key and has indexes select * from a join b on a.id=b.a_id question 1: is the above sql full table scan for a table and index for table b? select * from b ...
what should I do logically if I want to set the top (charge) while publishing information (free, charging)? How can the data table be designed properly? Has not been clear about the train of thought, hope that experienced gods to give guidance. which ...
there are two tables An and B, both of which are similar in structure. < hr > A form < table > < thead > < tr > < th > ID < th > < th > name < th > < th > state < th > < tr > < thead > < tbody > < tr > < td > 1 < td > < td > Zhang San < ...
docker-compose.yml file version: "3" services: mysql: build: . services mysql container_name: mysql ports: - ${MYSQL_PORT}:3306 volumes: - ${MYSQL_DATA_PATH}: var lib mysql:rw ...
when working on a project with reference to the materials on the Internet, if the last step of generating a kill order to the database fails because of the database itself, but the inventory in redis has been reduced and redis can not be rolled back, how...
this is the time in my database, it s a timestamp, I want to search or SQL statement search out the update_time field of the current month or the 1st-31st of a certain month ...
how do I invoke symfony s doctrine service to operate the database within a socket service? php website project done with symfony framework needs to use websocket service. The service written by socketio is started on the command line. Now it needs t...
the website made by myself has been attacked by others to visit a certain page or a certain method to make the website run very slow. how can such an attack be effectively prevented? Is there any other way to upgrade the server? thank you ...
sequelize query findone can return the first matched data then I want to get the last matched data. Is there a convenient way to or findAll to get all the data and then get the last ?...
should indicate that path has the wrong data type, but mine is from string . ...
the sum of the binaries stored in the mode field of the table, why do you find the data record of mode=28 using the query condition where mode & 5? where mode & 5 and where mode & 1 and mode & 4 query results are different, is there a boss to help ...
problem description customer table users has the following fields: there are 5 sales groups. Each sales group imports at least one batch of 100000 items of data into the table every month, and can only import the data of its own sales group ...