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Technical Articles

Database

Mysql Tutorial

Understanding Case Sensitivity Rules in MySQL

MySQL case rules depend on the operating system and configuration. 1. The case sensitivity of table names and database names depends on the operating system. By default, it is distinguished in Linux, Windows is not distinguished, and macOS is not distinguished, and is controlled by the lower_case_table_names parameter; 2. Column names are usually not case sensitive, but are affected by the SQL mode. Alias ??are recommended to be unified in style; 3. The comparison of field content is determined by character sets and sorting rules. Collation at the end of _ci is not case sensitive, and _cs or _bin is distinguished; 4. Development suggests uniformly using lowercase naming, keeping the environment consistent, clearly specifying the sorting rules, and paying attention to the handling of ORM tools.

Jul 05, 2025 am 02:45 AM

Aggregating data with GROUP BY and HAVING clauses in MySQL

GROUPBY is used to group data by field and perform aggregation operations, and HAVING is used to filter the results after grouping. For example, using GROUPBYcustomer_id can calculate the total consumption amount of each customer; using HAVING can filter out customers with a total consumption of more than 1,000. The non-aggregated fields after SELECT must appear in GROUPBY, and HAVING can be conditionally filtered using an alias or original expressions. Common techniques include counting the number of each group, grouping multiple fields, and filtering with multiple conditions.

Jul 05, 2025 am 02:42 AM

mysql group by

Paginating Results with LIMIT and OFFSET in MySQL

MySQL paging is commonly implemented using LIMIT and OFFSET, but its performance is poor under large data volume. 1. LIMIT controls the number of each page, OFFSET controls the starting position, and the syntax is LIMITNOFFSETM; 2. Performance problems are caused by excessive records and discarding OFFSET scans, resulting in low efficiency; 3. Optimization suggestions include using cursor paging, index acceleration, and lazy loading; 4. Cursor paging locates the starting point of the next page through the unique value of the last record of the previous page, avoiding OFFSET, which is suitable for "next page" operation, and is not suitable for random jumps.

Jul 05, 2025 am 02:41 AM

mysql Pagination

Automating MySQL backup and maintenance tasks

To realize automatic backup and maintenance of MySQL database, you can use the following methods: 1. Use the mysqldump command to combine shell scripts and crontab timing tasks to achieve daily automatic backups, and it is recommended to compress files, select non-system disk path storage, and regularly clean old backups; 2. Set up backup retention strategies, such as daily backups within 7 days and weekly backups within month and weekly backups through the find command, and delete expired files through the find command. Make sure that the backup has been uploaded before cleaning and avoid accidentally deleting other environmental data; 3. Use the MySQL event scheduler or external script to perform maintenance tasks such as optimization tables and analysis tables regularly, pay attention to avoiding business peaks and avoiding frequent optimization of large tables. These methods can effectively improve data security and system stability and reduce manual operations

Jul 05, 2025 am 02:39 AM

mysql backup Automated maintenance

Step-by-Step Guide to Installing MySQL Server

Definite steps are required to install and run the MySQL server. First prepare the system, update the software package, check disk space, and select the appropriate version; secondly, install it according to the operating system, configure the repository in Linux and install it with commands, and use the official installer in Windows; then start the service and confirm it is running normally; finally run the security script to set a strong password, clear anonymous users, disable remote root login, and adjust the configuration file to optimize the connection number and character set parameters. Follow these steps to ensure that MySQL runs safely and securely.

Jul 05, 2025 am 02:37 AM

Diagnosing and Reducing Replication Lag in MySQL

MySQL master-slave replication latency can be solved by locating causes and targeted optimization. 1. First determine the latency level, view the Seconds_Behind_Master value through SHOWSLAVESTATUS, and analyze the real delay with tools such as pt-heartbeat; 2. For excessive write pressure, you can upgrade the hardware, enable parallel replication or split slave libraries; 3. Avoid long transactions and slow queries, optimize master-slave SQL execution efficiency; 4. Check network conditions, reduce binlog content and enable compressed transmission; 5. Use multi-threaded replication in MySQL 5.7, and enable parallel replication based on logical clocks to improve throughput capabilities; 6. Appropriately tune the relaylog parameters and rebuild them regularly

Jul 05, 2025 am 02:31 AM

mysql Replication delay

Optimizing Slow Running Queries in a MySQL Database

TofixslowMySQLqueries,firstidentifyproblemqueriesusingtheslowquerylogandtoolslikept-query-digest.Second,analyzethemwithEXPLAINtofindfulltablescansormissingindexes.Third,optimizequeriesbyselectingonlyneededcolumns,avoidingfunctionsonindexedcolumns,sim

Jul 05, 2025 am 02:26 AM

mysql Query optimization

Best practices for MySQL database schema design

Designing an efficient and scalable MySQL database structure requires starting from four aspects: data type, indexing strategy, standardization and anti-standardization and naming specifications. 1. Reasonably select the field type. If INT is used instead of BIGINT, CHAR is better than VARCHAR (fixed length), and DATETIME or TIMESTAMP is preferred in the time field to avoid abuse of TEXT/BLOB, and enumeration classes can be used for ENUM or small table foreign keys; 2. Use the index correctly, do not create indexes in low-cardinal sequences, avoid fuzzy matching failure, combine indexes follow the principle of leftmost prefix, and regularly analyze slow query logs; 3. Fight normalization and anti-standardization, appropriately redundant commonly used fields to reduce JOIN, wide tables or JSON fields can be used for scenarios that read more and write less, but the number of needs to be prevented

Jul 05, 2025 am 02:19 AM

Using AUTO_INCREMENT for Generating Unique IDs in MySQL

Use AUTO_INCREMENT to automatically assign unique IDs without manual management. It is incremented from 1 by default. The ID will not be reused after deleting the record. The starting value can be set through ALTERTABLE. Different storage engines behave differently, such as InnoDB may skip certain values ??after restarting. Notes include avoiding manual insertion of duplicate IDs, considering conflict resolution during replication, choosing appropriate data types such as BIGINT, and scalability issues under high concurrency.

Jul 05, 2025 am 02:08 AM

mysql

Implementing Table Partitioning for Large Datasets in MySQL

MySQL partitions large tables to improve query performance and management efficiency. Selecting the appropriate partition type is the key: 1. RANGE is suitable for time or numerical range, such as logs are divided by date; 2. LIST is suitable for discrete values, such as region number; 3. HASH is used to uniformly distribute data, such as user ID; 4. KEY is automatically processed by MySQL, suitable for scenarios without obvious logic. The partition key needs to participate in the WHERE condition, avoid frequent column updates, and pay attention to the boundary value setting. Regular maintenance includes adding, merging, splitting, or deleting partitions. However, not all large tables are applicable. We need to consider the impact of data distribution, index usage and number of partitions on performance. We recommend that you make a decision after testing.

Jul 05, 2025 am 02:05 AM

Principles of MySQL Database Schema Optimization

MySQL database performance optimization should start with schema design. First, select the appropriate data type, such as using TINYINT instead of INT to represent the status, avoid abuse of TEXT/BLOB types, and use DATETIME and TIMESTAMP reasonably; second, use indexes reasonably, avoid indexing in low-base sequences, pay attention to the joint index order, regularly analyze SQL execution plans and clean up invalid indexes; third, balance the standardization and anti-standardization of table structure, appropriate redundancy reduces JOIN operations, but the application layer needs to maintain consistency; finally, unified naming specifications improve maintainability, such as using clear table names, field names and foreign key naming rules.

Jul 05, 2025 am 01:49 AM

mysql optimization

Selecting the Optimal Storage Engine for MySQL Tables

InnoDB is suitable for scenarios that require transactions, concurrent writes and crash recovery, such as e-commerce platforms or banking systems; MyISAM is suitable for static tables that require more reads, writes less, and does not require transactions, such as log systems; other engines such as Memory and Archive are suitable for specific purposes. When choosing, you should decide based on workload and data requirements, and InnoDB is recommended in most cases.

Jul 05, 2025 am 01:28 AM

mysql storage engine

Troubleshooting Common MySQL Connection Errors

When encountering MySQL connection problems, 1. First confirm whether the user name and password are correct, and check whether there are spelling errors or permission restrictions; 2. Ensure that the MySQL service is running normally, restart the service and view the logs if necessary; 3. Verify that the network is unobstructed, ensure that the port is open and there is no firewall blocking; 4. Check the binding address, connection limit and SSL settings in the MySQL configuration file to ensure that the configuration allows external connections.

Jul 05, 2025 am 01:24 AM

Troubleshooting mysql connection

Understanding MySQL error codes and common resolutions

Common MySQL errors include 1045 access denied, 2002 unable to connect to the local server, 1064SQL syntax error, and 1215 foreign key constraint failure. 1. Error 1045 requires checking the username, password, permission configuration and remote connection settings; 2. Error 2002 requires confirming the running status of MySQL service and socket path configuration; 3. Error 1064 requires checking the syntax, keyword usage and file format; 4. Error 1215 requires ensuring that the engine is InnoDB, the data type is consistent, and the reference column is indexed. Mastering these core problems and solutions can quickly deal with most MySQL errors.

Jul 05, 2025 am 12:48 AM

Error resolution mysql error