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Home

Technical Articles

Database

How to use indexes to improve performance in MySQL

Using indexes can significantly improve MySQL query performance and avoid full table scanning; 2. Indexes are suitable for accelerating WHERE, JOIN, ORDERBY and GROUPBY operations, but will increase write operation overhead and storage consumption; 3. Single columns, composite, prefix, unique or overlay indexes should be created according to query requirements, pay attention to the column order of composite indexes; 4. Avoid using functions and data types on index columns to mismatch or violate the leftmost prefix principle to ensure effective use of indexes; 5. Regularly use EXPLAIN to analyze query execution plans, remove unused or duplicated indexes, and update table statistics to optimize index effects.

Sep 07, 2025 am 06:04 AM

mysql database index

What is binary logging in MySQL?

BinarylogginginMySQLisessentialforreplication,point-in-timerecovery,andauditingasitrecordsalldataandstructurechangeslikeINSERT,UPDATE,DELETE,andDDLstatements,whileexcludingSELECTandnon-modifyingtransactions;itstoreseventsinbinaryformatcontainingSQLst

Sep 07, 2025 am 05:58 AM

mysql

How to perform an UPDATE from a SELECT statement in MySQL?

SELECT cannot be used directly in UPDATE in MySQL, but it can be implemented by combining UPDATE with JOIN, subquery or derived tables. The most effective method is to use UPDATE...JOIN, for example, UPDATEemployeesJOINsalariesONemployees.id=salaries.employee_idSETemployees.salary=salaries.amount; if you need to avoid the limitation of querying the same table when modifying the table, you can wrap the subqueries in the derived table; it is usually recommended to use the JOIN method, because it is concise, efficient and easy to understand, and you should always test SELEC first in the end.

Sep 07, 2025 am 05:44 AM

How to insert a new row into a table in SQL?

To insert a new row, use the INSERTINTO statement; 1. Specify the table name and the column name to insert the data; 2. Provide the corresponding order values ??in the VALUES clause; 3. When selecting a list of column names, make sure that the values ??exactly match the table structure; 4. Multiple rows can be inserted at one time to improve performance; 5. Pay attention to data types, constraints and syntax specifications, and this operation can be successfully executed.

Sep 07, 2025 am 05:34 AM

How to monitor a MySQL server

Enable slow query logs and analysis to monitor query performance; 2. Monitor key indicators such as connection number, buffer pool hit rate, lock waiting and replication delay; 3. Use tools such as PerformanceSchema, PMM, Prometheus to achieve visual monitoring; 4. Set alarm rules to promptly discover CPU, disk, connection number and replication delay abnormalities; 5. Regularly conduct log rotation, query mode review and index usage analysis to optimize long-term performance; effective MySQL monitoring should combine real-time observation, historical trend analysis and automated alarms to prevent problems in advance.

Sep 07, 2025 am 05:04 AM

What are user-defined functions in MySQL?

User-definedfunctions(UDFs)inMySQLarecustomfunctionscreatedbyuserstoextenddatabasefunctionality,withthemostcommontypebeingstoredfunctionswritteninSQL.Thesefunctionsreturnasinglescalarvalue,canbedeterministicornon-deterministic,andsupportinputparamete

Sep 07, 2025 am 04:25 AM

mysql 用戶自定義函數(shù)

How to Implement a Search Autocomplete Feature in MongoDB

Use regular expressions, prefix indexes, or MongoDBAtlasSearch to achieve automatic completion of MongoDB search: create indexes for fields and use $regex to achieve basic prefix matching, or pre-generate prefix arrays and create multi-key indexes to improve performance, or use the built-in autocomplete analyzer in Atlas to achieve efficient real-time suggestions.

Sep 07, 2025 am 03:28 AM

mongodb 搜索自動(dòng)完成

How to work with different character sets and collations in MySQL

To properly handle multilingual text, you must use the utf8mb4 character set and ensure that the settings at all levels are consistent. 1. Understand character sets and sorting rules: utf8mb4 supports all Unicode characters, utf8mb4_unicode_ci is used for general case-insensitive sorting, utf8mb4_bin is used for binary precise comparison; 2. Set default character sets and sorting rules at the server level through configuration files or SETGLOBAL; 3. Specify CHARACTERSETutf8mb4 and COLLATEutf8mb4_unicode_ci when creating a database, or modify it with ALTERDATABASE; 4. Character sets and sorting can also be defined at the table and column levels.

Sep 07, 2025 am 03:17 AM

mysql character set

What is the fastest way to export large datasets with Navicat?

ThefastestwaytoexportlargedatasetsinNavicatisbyoptimizingsettingsandenvironment.1.UsetheExportWizardwithfastformatslikeCSVorSQLdumps,disableunnecessaryheadersandformatting,andusemulti-rowinserts.2.FilterdatausingWHEREclausesortemporaryviewstoreducevo

Sep 07, 2025 am 02:54 AM

phpMyAdmin query builder tutorial

phpMyAdmin's QueryBuilder is a form-based interface, mainly used to visually build SELECT queries. 2. After logging in, select the database and click the "Query" tab to enter the interface. 3. Select the table in "From" to automatically connect based on foreign key association. 4. Check the required columns and support the use of COUNT, SUM and other functions. 5. Click "Addcondition" to set the WHERE condition, such as status='active'. 6. You can check "Groupby" to group the results, which is often used in aggregate functions. 7. Select the sorting sequence and ASC/DESC order. 8. Set the line limit such as LIMIT10 to avoid excessive output. 9. Click "

Sep 07, 2025 am 02:40 AM

phpMyAdmin edit table structure

After logging in to phpMyAdmin, select the database and table, and click the "Structure" tab to view the fields; 2. Click the edit icon next to the column to modify the name, type, length, default value, NULL settings, etc., note that changing the data type may cause data truncation; 3. Enter the quantity at the bottom of the structure page and click "Go" to add new columns in batches, or click the "Add Column" link to create one by one, and set the attributes and locations; 4. Click the "Delete" icon to remove the column, and use the "Move Column" function to adjust the column order; 5. After checking the column, click "Index", "Unique", "Primary Key" or "Full Text" to create an index, and manage existing indexes through the edit or delete buttons of the index area. The primary key needs to be deleted first and then rebuilt; data should be backed up before operation to avoid data loss due to changes

Sep 07, 2025 am 02:07 AM

SQL Dictionaries and Metadata Management

SQL dictionary is a collection of system tables that database records object information, which stores structure information and affects query efficiency and permission control; metadata management describes data, involving permissions, comments, sources and other information, and is the basis of data governance. The SQL dictionary is accessed through INFORMATION_SCHEMA or system view to help quickly understand the structural details such as field type and whether it is allowed to be empty; metadata management requires unified data meaning and avoid ambiguity, especially in data migration and ETL; when using it, you need to pay attention to performance issues, permission restrictions, cross-store differences and untimely updates. For example, in PostgreSQL, you should use the pg_size_pretty function to view table size instead of looking up the system table.

Sep 07, 2025 am 01:32 AM

How to view database server variables in Navicat?

TocheckservervariablesinNavicat,youcanusethreemethods:1)Viewvariablesviaserverconnectionpropertiesbyeditingtheconnectionandnavigatingtothe"Advanced"tabwhereinitialserversettingsaredisplayed.2)Usethebuilt-inServerMonitortoolunderthe"Too

Sep 07, 2025 am 01:22 AM

navicat database server

Install Redis: Security best options

ThebestsecurityoptionsforinstallingRedisinclude:1)BindingRedistolocalhosttopreventexternalaccess,2)Settingastrongpasswordmanagedsecurely,3)DisablingdangerouscommandslikeFLUSHALLandCONFIG,4)ImplementingTLS/SSLencryptionusingtoolslikestunnel,5)Regularl

Sep 07, 2025 am 01:16 AM