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Home

Technical Articles

Database

Mysql Tutorial

Creating a New Database and User Account in MySQL

To create a new database and user in MySQL and assign permissions, you need to follow the following steps: 1. After logging in to MySQL, use CREATEDATABASE to create a database, which can specify the character set and sorting rules; 2. Use CREATEUSER to create a user and set a password to specify the host that is allowed to connect; 3. Assign corresponding permissions through GRANT, such as ALLPRIVILEGES or SELECT, INSERT, etc., and refresh the permissions with FLUSHPRIVILEGES. The entire process requires attention to correct syntax, reasonable permission control and password security to avoid failure due to misspelling or improper configuration.

Jul 04, 2025 am 12:20 AM

mysql database

Understanding the role of foreign keys in MySQL data integrity

ForeignkeysinMySQLensuredataintegritybyenforcingrelationshipsbetweentables.Theypreventorphanedrecords,restrictinvaliddataentry,andcancascadechangesautomatically.BothtablesmustusetheInnoDBstorageengine,andforeignkeycolumnsmustmatchthedatatypeoftherefe

Jul 03, 2025 am 02:34 AM

Best ways to handle NULL values in MySQL queries

When handling NULL values ??in MySQL queries, you need to pay attention to their characteristics that represent "unknown" or "not exist", and cannot be judged by ordinary comparison characters. 1. Use ISNULL and ISNOTNULL to filter or exclude NULL values, such as WHEREemailISNULL or WHEREemailISNOTNULL. 2. Replace the NULL value with IFNULL() or COALESCE(). IFNULL(col,'default') is used in two-parameter scenarios. COALESCE(col1,col2,...,default) returns the first non-NULL value. 3. Handle NULL with caution in JOIN or WHERE clauses, LEFTJOI

Jul 03, 2025 am 02:33 AM

mysql null value

Resetting the root password for MySQL server

To reset the root password of MySQL, please follow the following steps: 1. Stop the MySQL server, use sudosystemctlstopmysql or sudosystemctlstopmysqld; 2. Start MySQL in --skip-grant-tables mode, execute sudomysqld-skip-grant-tables&; 3. Log in to MySQL and execute the corresponding SQL command to modify the password according to the version, such as FLUSHPRIVILEGES;ALTERUSER'root'@'localhost'IDENTIFIEDBY'your_new

Jul 03, 2025 am 02:32 AM

mysql reset Password

Monitoring MySQL server health and performance metrics

Monitoring MySQL health and performance requires attention to five core dimensions. 1. Check the number of connections and thread status, and use SHOWSTATUSLIKE'Threads%'; view Threads_connected and Threads_running. If Threads_running is higher than 10~20 for a long time, you need to combine the slow query log troubleshooting; 2. Enable and analyze the slow query log, configure slow_query_log, long_query_time, use mysqldumpslow or pt-query-digest analysis to optimize the SQL of the missed index; 3. Monitor the InnoDB status and pay attention to the buffer pool hit rate and log

Jul 03, 2025 am 02:31 AM

Performance mysql monitoring

Tuning MySQL memory usage for optimal performance

MySQL memory tuning needs to be reasonably configured based on load, data volume and hardware. Key parameters include: 1. Innodb_buffer_pool_size is recommended to set to 50%~80% of physical memory, but does not exceed the actual data requirements; 2. key_buffer_size is suitable for MyISAM engine, and InnoDB users can keep it small; 3. query_cache_type and query_cache_size are easily bottlenecks in scenarios that write more and read less, and MySQL8.0 has been removed; 4. max_connections and thread-level buffers need to control the total amount to avoid memory overflow. Before tuning, you should pass top, SHOWENGINEINNODBS

Jul 03, 2025 am 02:30 AM

mysql performance Memory optimization

Optimizing GROUP BY and ORDER BY clauses in MySQL

The key to optimizing GROUPBY and ORDERBY performance is to use matching indexes to speed up queries. 1. Create a composite index for the columns involved in GROUPBY, and the order must be consistent, so as to avoid using functions on the columns; 2. Ensure that the ORDERBY column is overwritten by the index and try to avoid sorting large result sets; 3. When GROUPBY and ORDERBY coexist, if the sorting is based on aggregate values, the index cannot be used. Consider limiting the number of rows or pre-calculating the aggregate value; 4. Check and remove unnecessary grouping or sorting, reduce data processing, and improve overall efficiency.

Jul 03, 2025 am 02:30 AM

mysql optimization

Implementing point-in-time recovery for MySQL databases

TorestoreaMySQLdatabasetoaspecificpointintime,firstensureyouhaveafullbackupandbinarylogsenabled.1)Enablebinaryloggingbyconfiguringlog_binandserver_idinmy.cnf/my.iniandoptionallysetexpire_logs_days.2)Restorethelatestfullbackupusingmysql-uroot-p

Jul 03, 2025 am 02:27 AM

Configuring connection pooling for MySQL applications

Connection pooling can effectively reduce the overhead of frequently creating and destroying connections and avoid database connection exhaustion. 1. Each time a new connection is established, it consumes resources and time. Under high concurrency, it will lead to increased latency, increased load and exceeded the maximum number of connections limit; 2. The connection pool is pre-created at the application startup and reused after use to improve efficiency and control resource consumption; 3. The selection needs to consider performance (such as HikariCP), feature richness (such as Druid), integration, community support, etc.; 4. The core configuration includes the minimum number of idle connections (5~10), maximum number of connections (no more than 80% of the database limit), connection timeout (within 30s), idle timeout (several minutes to more than ten minutes), etc.; 5. Common misunderstanding is that the maximum number of connections is set too large, and it should be combined with pressure measurement and adjustment.

Jul 03, 2025 am 02:26 AM

mysql connection pool

Exploring MySQL geographic data types and functions

MySQLsupportsgeographicdatatypesandfunctionsforlocation-basedapplications.①ItoffersspatialtypeslikePOINT,LINESTRING,POLYGON,andGEOMETRYCOLLECTIONtostoregeometricdata.②UserscaninsertandquerydatausingWKTformatwithfunctionslikePOINT()andST_Distance_Sphe

Jul 03, 2025 am 02:23 AM

Securing your MySQL database against common threats

To improve the security of MySQL database, we need to start from four aspects: access control, password management, backup mechanism and minimize configuration. Specifically, it includes: 1. Restrict access permissions, only allow specific IP connections and create a dedicated account; 2. Use a strong password and enable authentication plug-ins, such as validate_password; 3. Regularly backup data and test the recovery process to ensure that the data can be restored; 4. Turn off unnecessary functions and services, such as deleting test databases, disabling anonymous users and unwanted plug-ins. These measures can effectively prevent most common threats and ensure the safe and stable operation of the database.

Jul 03, 2025 am 02:18 AM

Resolving deadlocks in MySQL applications

MySQL deadlock is caused by multiple transactions being cross-waited for resources, and can be reduced by unified access order, shortening transaction time, and rational use of indexes. For example, when transaction A and transaction B hold different resources respectively and request each other's resources, a deadlock will be formed; through the SHOWENGINEINNODBSTATUS command, you can view detailed deadlock logs, analyze transaction SQL, lock types and related rows; during development, access orders should be unified to avoid orders first and then users or the opposite; shorten transaction execution time and reduce lock occupation; ensure that WHERE conditions hit indexes to reduce lock range; batch updates are sorted by primary keys; the application layer captures 1213 error codes and retrys transactions; occasional deadlocks are normal, and frequent occurrences require combining logs and business optimization.

Jul 03, 2025 am 02:13 AM

mysql deadlock

Working with JSON data types in MySQL

MySQL supports JSON data types since 5.7, which can be used to store and operate JSON data; 1. When storing, you need to use JSON type fields and ensure the format is correct; 2. You can query the JSON_EXTRACT or -> operator to extract the field values; 3. Modify functions such as JSON_SET to update the content; 4. In terms of performance, you cannot directly index internal fields, which can be implemented by generating columns; 5. JSON is more suitable for scenarios where more reads, fewer writes and less structures are not complicated.

Jul 03, 2025 am 02:10 AM

Improving MySQL full-text search performance

To improve the full-text search performance of MySQL, it is necessary to optimize from index, configuration, query statements and external tools. 1. Use full-text index reasonably, avoid redundant fields and whole table indexes, use prefix indexes appropriately and customize stop words; 2. Adjust system parameters such as ft_min_word_len and InnoDB full-text cache size, and execute OPTIMIZETABLE regularly; 3. Optimize query statements, limit wildcard usage, add filter conditions, and cooperate with LIMIT paging; 4. High-demand scenarios can introduce external search engines such as Elasticsearch to improve capabilities and reduce the burden on MySQL.

Jul 03, 2025 am 02:03 AM

mysql research all