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181. Employees who exceed the manager's income Employee The table contains all employees, and their managers belong to employees. Every employee has one Id，In addition, there is a list of managers corresponding to employees Id. +----+-------+--------+-----------+ | Id | Name | Salary | ManagerId | +----+-------+--------+-----------+ | 1 | ...

1, Data We talked about the log before the database drop. Today, it's very troublesome to analyze the data drop. But the principle is the same. In the previous analysis, we can clearly know that in MySql, no matter what kind of data, it enters the cache first, and then drops the disk to save. In the database, what is the most important? Of cou ...

scene Winform establishes a connection with Mysql8 and obtains all tables, then checks the specified table, regularly backs up the database and exports it as an sql file. And you can set the number of overwriting backups. For example, if it is set to 7, the sql file backed up for the first time will be replaced when backing up to the eighth ti ...

Install MySql database 1. Search the mysql image on hub.docker.com 2. Pull the specified version of mysql. You can also specify the pull version, for example: docker pull mysql:8.0.23 3. Check mysql image docker images 4. Start and run mysql image (docker run is used to start a container) sudo docker run -p 3306:3306 --name mysql \ -v ...

1 ES data organization concept The data organization concept of ES is compared with MySQL and MongoDB as follows:( "Most popular" basis) Note that the concept of ES Index here is similar to that of MySQL database, which is easy to be confused later. What is more noteworthy is that after ES6, multiple types are not allowed in ...

###Title Practice sql Download: 1. Query the number of students selected for each course; 2. Find out the student numbers and names of all students who have taken only one course; 3. Query the number of boys and girls; 4. Check the list of students surnamed "Zhang"; 5. Query the list of students with the same name and surname, and cou ...

Authority management -- Create a new user create user sinanshao identified by '123456'; -- Change Password alter user 'sinanshao'@'%' identified by '111111'; -- Change user name rename sinanshao to sinanshao2; -- delete user drop user sinanshao; -- User authorization,Give the user all permissions -- all privileges All permissions except au ...

Mind map 1, Application scenario of partition table 1. The table is so large that it cannot be put in memory, or there is only hot data in the last part of the table, and others are historical data2. Partition table data is easier to maintain You can delete a large amount of data in batch by clearing the entire partition Optimize, check ...

1, Introduction to e-commerce business 1.1 e-commerce business process The business process of e-commerce can be illustrated by taking the browsing footprint of an ordinary user as an example. Users click the home page of e-commerce to start browsing. They may find their favorite products through classified query or full-text search. Thes ...

Database Note 02 SQL Statement (bottom) +MySQL Constraint 1. Detailed syntax of query statements in SQL: Query all data in the table: select * from surface -- It's actually recommended that you write out all the field names Query individual fields: select Field name 1,Field Name 2 from surface Conditional Query: select field from ...