mysqldump is a common tool for performing logical backups of MySQL databases. It generates SQL files containing CREATE and INSERT statements to rebuild the database. 1. It does not back up the original file, but converts the database structure and content into portable SQL commands; 2. It is suitable for small databases or selective recovery, and is not suitable for fast recovery of TB-level data; 3. Common options include --single-transaction, --databases, --all-databases, --routines, etc.; 4. Use mysql command to import during recovery, and can turn off foreign key checks to improve speed; 5. It is recommended to test backup regularly, use compression, and automatic adjustment.

To safely handle PHP file uploads, you need to verify the source and type, control the file name and path, set server restrictions, and process media files twice. 1. Verify the upload source to prevent CSRF through token and detect the real MIME type through finfo_file using whitelist control; 2. Rename the file to a random string and determine the extension to store it in a non-Web directory according to the detection type; 3. PHP configuration limits the upload size and temporary directory Nginx/Apache prohibits access to the upload directory; 4. The GD library resaves the pictures to clear potential malicious data.

InPHP,variablesarepassedbyvaluebydefault,meaningfunctionsorassignmentsreceiveacopyofthedata,whilepassingbyreferenceallowsmodificationstoaffecttheoriginalvariable.1.Whenpassingbyvalue,changestothecopydonotimpacttheoriginal,asshownwhenassigning$b=$aorp

To set up asynchronous master-slave replication for MySQL, follow these steps: 1. Prepare the master server, enable binary logs and set a unique server-id, create a replication user and record the current log location; 2. Use mysqldump to back up the master library data and import it to the slave server; 3. Configure the server-id and relay-log of the slave server, use the CHANGEMASTER command to connect to the master library and start the replication thread; 4. Check for common problems, such as network, permissions, data consistency and self-increase conflicts, and monitor replication delays. Follow the steps above to ensure that the configuration is completed correctly.

Usefortaskcompletionandforstaticmeasurements.1.showshowfaralongataskis,eitherindeterminate(unknownduration)ordeterminate(percentageknown).2.displaysacurrentvaluewithinafixedrange,likescoresortemperature,withoptionallow,high,andoptimalthresholds.3.Avo

To view the size of the MySQL database and table, you can query the information_schema directly or use the command line tool. 1. Check the entire database size: Execute the SQL statement SELECTtable_schemaAS'Database',SUM(data_length index_length)/1024/1024AS'Size(MB)'FROMinformation_schema.tablesGROUPBYtable_schema; you can get the total size of all databases, or add WHERE conditions to limit the specific database; 2. Check the single table size: use SELECTta

Database schema migration refers to the process of modifying the database structure without changing the data, which mainly includes adding or deleting tables, modifying column types or constraints, creating or deleting indexes, changing default values ??or nullable settings, etc. It is usually driven by application updates, for example, when new features need to store user preferences, new columns are added to the user table. Unlike data migrations that deal with large amounts of data movement, pattern migration focuses on structural changes. To perform mode migrations safely, version control should be used to track structure files, verify them in the test environment before the production environment, split the large migration into small steps, avoid multiple irrelevant changes in a single time, and note that changes to large tables may cause long-term table locking problems. You can use tools such as pt-online-schema-chan.

The most direct way to connect to MySQL database is to use the command line client. First enter the mysql-u username -p and enter the password correctly to enter the interactive interface; if you connect to the remote database, you need to add the -h parameter to specify the host address. Secondly, you can directly switch to a specific database or execute SQL files when logging in, such as mysql-u username-p database name or mysql-u username-p database name