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Technical Articles

Database

Mysql Tutorial

how to connect to mysql database from php

Common ways to connect to MySQL databases are to use mysqli extensions and PDO. 1. Use mysqli to extend the recommended object-oriented method, with clear code, and you need to ensure that extension=mysqli is enabled in php.ini; 2. Use PDO to be suitable for compatible with multiple databases, supports exception handling and set character set to utf8mb4. Frequently asked questions include username and password errors, database does not exist, host or port is incorrect, PHP extension is not enabled, and firewall restrict access. These issues should be checked one by one to ensure successful connection.

Jul 31, 2025 am 09:20 AM

A Deep Dive into MySQL JSON Data Type Capabilities

MySQL's JSON data types provide powerful functions, not only storing structured and semi-structured data, but also support verification, query and modification. First, it automatically verifies the JSON format to ensure data integrity; secondly, it can efficiently query data through functions such as JSON_EXTRACT() and support generating column indexes to improve performance; finally, using functions such as JSON_SET() to accurately update part of the data to avoid rewriting the entire document. Rationally utilizing these tools can effectively process JSON data in a production environment.

Jul 31, 2025 am 09:06 AM

Optimizing MySQL for Read-Heavy Workloads

ToimproveMySQLperformanceforread-heavyworkloads,followthesesteps:1.Usetherightindexingstrategybyaddingindexesonfrequentlyqueriedcolumns,especiallyinWHEREclausesandJOINconditions,whileavoidingover-indexingandconsideringcompositeindexesformulti-columnq

Jul 31, 2025 am 08:44 AM

mysql Performance optimization

Troubleshooting MySQL Server Crashing Issues

MySQL service crashes are usually caused by insufficient resources, configuration errors, hardware problems or software conflicts, and the troubleshooting needs to be carried out in steps. 1. First check the MySQL error log to find warnings or error messages before crashes, such as insufficient memory, table space loss, etc., and it is recommended to monitor the log regularly. 2. Check the use of system resources, including memory, CPU and disk space. It is recommended to use monitoring tools and reasonably set the InnoDB buffer pool size. 3. Check the rationality of MySQL configuration, such as the maximum number of connections, log file size and other parameters. It is recommended to use MySQLTuner to analyze and back up the configuration file before modifying it. 4. Troubleshoot hardware or system problems, such as hard disk failure, system update impact, permission restrictions, etc. It is recommended to view the system log and I/

Jul 31, 2025 am 07:23 AM

Implementing MySQL Failover Automation with Keepalived

MySQL failover automation can be implemented through Keepalived. The core is 1. Use custom scripts to monitor MySQL status, such as detecting survival and replication status through mysqladminping; 2. Configure VIP to achieve automatic drift, and the client connects VIP instead of specific hosts; 3. Switch data consistency after processing, it is recommended to enable semi-synchronous replication, add delay judgment logic, and rebuild the replication topology with other tools.

Jul 31, 2025 am 05:17 AM

Applying WHERE and HAVING Clauses for Filtering Data in MySQL

The core difference between WHERE and HAVING is the filtering timing: 1. WHERE filters rows before grouping, which are used to exclude original records that do not meet the conditions; 2. HAVING filters the aggregate results after grouping, which are used to filter groups that meet the conditions. For example, when querying active employees, use WHEREstatus='active', and when screening department users exceed 5, use HAVINGemployee_count>5; the two can also be used in combination, first reduce the amount of data through WHERE, and then filter the aggregated results through HAVING. For example, first filter full-time employees and then filter departments with an average salary of more than 60,000. Correct use of both can improve query efficiency and accuracy.

Jul 31, 2025 am 04:44 AM

mysql Data filtering

Securing MySQL with Database Firewalls

Database firewalls can effectively improve MySQL security. Specific methods include: 1. Use a whitelist mechanism to restrict access sources; 2. Intercept high-risk statements through SQL syntax analysis; 3. Implement user permission isolation strategies; 4. Set blacklist rules to block known attack modes; 5. Combining open source or commercial tools to achieve protection; at the same time, pay attention to rule configuration, log audit and performance evaluation, so as to ensure security without affecting normal business.

Jul 31, 2025 am 04:08 AM

mysql select rows that are not in another table

To select rows from one table that have no corresponding records in another table, MySQL provides three common methods. 1. Use LEFTJOIN ISNULL: By leftjoining the main table to the target table and filtering records with the right table as null, the performance is usually better and the logic is clear; 2. Use NOTIN: intuitive but note that if the subquery results include NULL, it will cause the entire condition to fail, which is suitable for situations where the data volume is not large; 3. Use NOTEXISTS: Similar to LEFTJOIN, but it is safer and supports multiple condition matching. It is recommended to use in production environments. When choosing, index, data structure and performance requirements must be considered comprehensively.

Jul 31, 2025 am 03:26 AM

mysql not in

Troubleshooting MySQL Disk Space Issues and Cleanup

When the MySQL database has insufficient disk space, you can check and clean it as follows: 1. Use df-h and du-sh/var/lib/mysql/* to check the usage of disk and MySQL files; 2. Clean the binary logs, delete the old logs by time or file name through PURGEBINARYLOGS, or set expire_logs_days automatically clean up in my.cnf; 3. Delete databases or tables that are no longer used, confirm that they are useless and make backups before executing DROPDATABASE or DROPTABLE; 4. Use OPTIMIZETABLE to recycle InnoDB tablespace fragments, be careful to reserve enough space to execute; 5. Deploy monitoring tools

Jul 31, 2025 am 03:13 AM

mysql disk space

Troubleshooting MySQL Performance Degradation Over Time

Common reasons for MySQL performance decline over time include slow queries, unreasonable index design, poor table structure design and system resource bottlenecks. 1. Enable slow query logs and combine EXPLAIN to analyze execution plans to find time-consuming SQL and optimize; 2. Check index usage to avoid missing, inefficient or excessive indexes, and reasonably create joint indexes; 3. Regularly maintain table structure, optimize field types, execute ANALYZETABLE and OPTIMIZETABLE, and consider large table partitioning; 4. Monitor system resources and adjust configuration parameters such as innodb_buffer_pool_size to match hardware capabilities. The above methods can be used to effectively troubleshoot and improve performance.

Jul 31, 2025 am 02:17 AM

Optimizing MySQL for Analytics and Data Warehousing

MySQLcanhandleanalyticsworkloadswithproperoptimization.Toimproveperformance,useInnoDBformixedOLTP/OLAPscenarios,considerMyRocksorColumnStoreforread-heavytables,andapplypartitioningforlargedatasets.Denormalizeschemasstrategically,createsummarytables,a

Jul 31, 2025 am 12:27 AM

MySQL Database Performance Baseline Establishment

To establish a MySQL database performance baseline, first clarify key indicators, collect data and observe trends, establish a benchmark model, and update dynamically. 1. Determine monitoring indicators, including CPU usage, memory usage, disk I/O, number of connections, number of slow queries, QPS/TPS, and collect them using tools such as SHOWSTATUS or PMM. 2. Continue to collect data from different time periods, retain it for at least one week, and establish a reasonable baseline based on business peak periods and special periods. 3. Extract typical performance, compare data in the same time period using mean, peak, and percentile, and define anomaly threshold. 4. Update the baseline regularly or after system changes, and use automation tools to adapt to environmental changes to ensure that the baseline always reflects the real operating status.

Jul 30, 2025 am 04:10 AM

Implementing MySQL Database Auditing Best Practices

Enable MySQL built-in audit function, and enable logging by installing the audit_log.so plug-in and configuring parameters; 2. Regularly review logs, use automation tools to analyze and set alerts to ensure storage security; 3. Implement the principle of minimum permissions, assign necessary permissions and regularly review and revoke unnecessary permissions. MySQL database auditing needs to be combined with technical configuration and management supervision to ensure data security and compliance.

Jul 30, 2025 am 03:58 AM

Migrating Data to MySQL: Best Practices and Tools

TomovedataintoMySQLefficiently,firstunderstandyourdatasources,thenchooseappropriatetools,cleandatabeforehand,andmonitorperformance.Beginbyidentifyingthesourceformat—CSV,Excel,otherdatabases,orAPIs—asthisdeterminesthemigrationmethod.Next,selecttoolsli

Jul 30, 2025 am 03:54 AM