In MySQL, add fields using ALTERTABLEtable_nameADDCOLUMNnew_columnVARCHAR(255)AFTERexisting_column, delete fields using ALTERTABLEtable_nameDROPCOLUMNcolumn_to_drop. When adding fields, you need to specify a location to optimize query performance and data structure; before deleting fields, you need to confirm that the operation is irreversible; modifying table structure using online DDL, backup data, test environment, and low-load time periods is performance optimization and best practice.

The gitstatus command is used to display the status of the working directory and temporary storage area. 1. It will check the current branch, 2. Compare the working directory and the temporary storage area, 3. Compare the temporary storage area and the last commit, 4. Check untracked files to help developers understand the state of the warehouse and ensure that there are no omissions before committing.

The steps to deploy a Joomla website on PhpStudy include: 1) Configure PhpStudy, ensure that Apache and MySQL services run and check PHP version compatibility; 2) Download and decompress PhpStudy's website from the official Joomla website, and then complete the installation through the browser according to the installation wizard; 3) Make basic configurations, such as setting the website name and adding content.

The steps to start system restore in Windows 8 are: 1. Press the Windows key X to open the shortcut menu; 2. Select "Control Panel", enter "System and Security", and click "System"; 3. Select "System Protection", and click "System Restore"; 4. Enter the administrator password and select the restore point. When selecting the appropriate restore point, it is recommended to select the restore point before the problem occurs, or remember a specific date when the system is running well. During the system restore process, if you encounter "The system restore cannot be completed", you can try another restore point or use the "sfc/scannow" command to repair the system files. After restoring, you need to check the system operation status, reinstall or configure the software, and re-back up the data, and create new restore points regularly.

Visiting the latest address to Binance official website can be obtained through search engine query and follow official social media. 1) Use the search engine to enter "Binance Official Website" or "Binance" and select a link with the official logo; 2) Follow Binance's official Twitter, Telegram and other accounts to view the latest posts to get the latest address.

There are three ways to view the process information inside the Docker container: 1. Use the dockertop command to list all processes in the container and display PID, user, command and other information; 2. Use dockerexec to enter the container, and then use the ps or top command to view detailed process information; 3. Use the dockerstats command to display the usage of container resources in real time, and combine dockertop to fully understand the performance of the container.

In Unity, 3D physics engines and AI behavior trees can be implemented through C#. 1. Use the Rigidbody component and AddForce method to create a scrolling ball. 2. Through behavior tree nodes such as Patrol and ChasePlayer, AI characters can be designed to patrol and chase players.

The reasons for file deletion failure during Apache uninstall include file permission issues, locking files, and running processes. Solutions include: 1. Stop the Apache service: sudosystemctlstoppapache2; 2. Manually delete the Apache directory: sudorm-rf/etc/apache2/usr/sbin/apache2; 3. Use lsof to find and terminate the process of locking the file: sudolsof|grepapache2, and then sudokill-9; 4. Try to delete the file again.