超碰cao已满18进入离开官网,xx另类性欧美,av色图

Article Tags

All
web3.0
- All
- NoSQL database
- Memcached
- cloudera
- memcache
Backend Development
- All
- PHP Tutorial
- Python Tutorial
- Golang
- XML/RSS Tutorial
- C#.Net Tutorial
- C++
- NoSQL database
- Memcached
- cloudera
- memcache
Web Front-end
Database
- All
- Mysql Tutorial
- navicat
- SQL
- Redis
- phpMyAdmin
- Oracle
- MongoDB
- NoSQL database
- Memcached
- cloudera
- memcache
Operation and Maintenance
- All
- Mac OS
- Linux Operation and Maintenance
- Apache
- Nginx
- CentOS
- Docker
- NoSQL database
- Memcached
- cloudera
- memcache
Development Tools
- All
- VSCode
- sublime
- notepad
- git
- composer
- NoSQL database
- Memcached
- cloudera
- memcache
PHP Framework
- All
- Laravel
- YII
- NoSQL database
- Memcached
- cloudera
- memcache
Common Problem
- All
- NoSQL database
- Memcached
- cloudera
- memcache
Other
- All
- IIS
- SEO
- Premiere
- NoSQL database
- Memcached
- cloudera
- memcache
Tech
- All
- AI
- It Industry
- NoSQL database
- Memcached
- cloudera
- memcache
CMS Tutorial
- All
- WordPress
- NoSQL database
- Memcached
- cloudera
- memcache
Java
- All
- javaTutorial
- NoSQL database
- Memcached
- cloudera
- memcache
System Tutorial
- All
- Windows Series
- LINUX
- MAC
- NoSQL database
- Memcached
- cloudera
- memcache
Computer Tutorials
Hardware Tutorial
Mobile Tutorial
- All
- Mobile News
- iPhone
- Android Phone
- NoSQL database
- Memcached
- cloudera
- memcache
Software Tutorial
Mobile Game Tutorial

Home

Technical Articles

Database

Optimizing MySQL for Collaborative Editing Applications

Optimizing MySQL to support collaborative editing applications similar to GoogleDocs requires starting from isolation level, pattern design, indexing strategy, etc. First, use the READCOMMITTED isolation level to reduce lock contention and set the global transaction isolation level; second, design event tables to store user operations rather than full document status to avoid row lock conflicts; third, establish (document_id, timestamp) composite indexes and control the number of indexes; fourth, enable deadlock log monitoring and optimize transaction size and execution order; fifth, reasonably use connection pools and application layer caches instead of query cache. These adjustments can improve responsiveness and data consistency under high concurrency.

Aug 08, 2025 pm 02:41 PM

mysql 協(xié)同編輯

What is the ALTER TABLE statement in SQL?

TheALTERTABLEstatementisusedtomodifyanexistingtable’sstructurewithoutrecreatingit;1.AddanewcolumnusingADDCOLUMN;2.DropacolumnwithDROPCOLUMN,whichalsodeletesitsdata;3.RenameacolumnusingRENAMECOLUMN,withsyntaxconsistentinMySQL,SQLServer,andPostgreSQL;4

Aug 08, 2025 pm 02:13 PM

sql

What is the MERGE statement in SQL and how does it work?

TheMERGEstatementinSQLenablesconditionaldatasynchronizationbyperformingINSERT,UPDATE,orDELETEoperationsonatargettablebasedonmatcheswithasourcedataset.1)WhenarowmatchestheONcondition,itexecutesWHENMATCHEDTHENUPDATE(orDELETE).2)Whennomatchexistsintheta

Aug 08, 2025 pm 02:12 PM

sql MERGE語句

How to use OUTPUT clause to get inserted or deleted values in SQL?

TheOUTPUTclausecapturesdataaffectedbyDMLoperations:useinsertedtoretrievenewvaluesafterINSERTorUPDATE;2.UsedeletedtocaptureoldvaluesbeforeDELETEorUPDATE;3.CombineinsertedanddeletedinUPDATEstatementstotrackbefore-and-afterchanges;4.RedirectOUTPUTresult

Aug 08, 2025 pm 01:45 PM

How to log errors in a table in SQL?

Yes,SQLdoesnotlogerrorstousertablesbydefault—youmustcreateacustomerrorloggingmechanism.1.CreateanErrorLogtablewithfieldslikeErrorTime,ErrorMessage,ErrorSeverity,ProcedureName,andAdditionalInfotostoreerrordetails.2.InSQLServer,useTRY-CATCHblockswithin

Aug 08, 2025 pm 12:32 PM

Securing MySQL with Privileged Access Management (PAM)

MySQL requires PAM because its default authentication mechanism may have problems such as password sharing, dispersed user management and insufficient auditing in an enterprise environment. 1. PAM can integrate LDAP, Radius or Kerberos to achieve unified authentication; 2. Improve audit capabilities and record login logs; 3. Support multi-factor authentication such as OTP; 4. Control access source and time. When configuring, you need to ensure that the plug-in supports, install the PAM library, create users and configure policy files. When using it, pay attention to fine control of permissions, configuration testing, logging inspection and avoiding circular dependencies.

Aug 08, 2025 pm 12:22 PM

mysql authority management

How to Store JSON Data in MySQL and Query It?

Use MySQL5.7 and above to store and query JSON data directly through JSON data types; 2. Define JSON columns when creating a table and insert legal JSON data, MySQL will automatically verify its validity; 3. Use the -> and -> operators to extract JSON field values, among which ->> can be used to remove string quotations for comparison; 4. Search for JSON content in WHERE clauses through functions such as JSON_CONTAINS, CAST, etc., and note that numerical comparison requires type conversion; 5. Use the JSON_SET, JSON_REPLACE and JSON_REMOVE functions to modify the JSON field; 6. Although it cannot be straightforward

Aug 08, 2025 pm 12:02 PM

mysql query json data

What is the PIVOT operator in SQL Server and how do you use it?

PIVOTinSQLServertransformsrowdataintocolumnsbyaggregatingvaluesandrotatinguniqueentriesfromonecolumnintonewcolumnheaders,idealforcreatingsummaryreports.Itperformsthreeoperations:aggregationusingfunctionslikeSUMorCOUNT,groupingbynon-pivotedcolumns,and

Aug 08, 2025 am 11:44 AM

How to fix 'Too many connections' error in MySQL

Checkmax_connectionsandThreads_connectedtoconfirmthelimitandcurrentusage.2.Increasemax_connectionstemporarilywithSETGLOBALorpermanentlyviamy.cnf/my.ini.3.Useconnectionpooling,closeconnectionsexplicitly,andmanagepersistentconnectionsintheapplication.4

Aug 08, 2025 am 11:37 AM

mysql Database Connectivity

How to manage foreign key constraints in MySQL

DefineforeignkeysduringtablecreationusingFOREIGNKEYwithREFERENCESandspecifyONDELETE/ONUPDATEactionslikeCASCADEtomaintainreferentialintegrity.2.AddforeignkeyconstraintstoexistingtablesviaALTERTABLEwithADDCONSTRAINT,ensuringmatchingcolumntypesandindexe

Aug 08, 2025 am 11:26 AM

What is Lua scripting in Redis?

Execution in Redis with Lua scripts has the advantages of atomicity, reducing network round trips, and simplifying application logic. The core reason is that multiple operations are encapsulated into a script through the EVAL or EVALSHA commands to ensure the atomic execution of operations and avoid race conditions; 1. Reduce the number of communications between the client and the server; 2. Make complex operation logic complete at one time on the server; 3. Improve performance and enhance code maintainability. Best practices should be followed when using: keep the script concise and fast, avoid large-scale loops, use local variables, test the scripts fully, and handle errors with caution. Not suitable for scenarios where external API calls, recalculation tasks, or multi-key cross-slot operations are required.

Aug 08, 2025 am 10:39 AM

How to return a default value if a column is NULL in SQL?

Using the COALESCE() function is the best general way to process NULL values and return default values, because it is supported in most database systems; 1. Use COALESCE(column_name,'default_value') when database portability is required, which is suitable for PostgreSQL, SQLServer, MySQL, Oracle, and SQLite; 2. If only SQLServer is used, ISNULL(column_name,'default_value'); 3. If only MySQL is used, IFNULL(column_name,'default_value');

Aug 08, 2025 am 10:30 AM

sql null value

What is the difference between a function and a view in SQL?

ViewsarevirtualtablesbasedonaSELECTquery,usedtosimplifyqueriesorrestrictaccess,whilefunctionsarereusableroutinesthatreturnavalueorresultset.2.Viewscannotacceptparameters,whereasfunctionscan.3.Viewsalwaysreturnatable-likeresultset,whilefunctionscanret

Aug 08, 2025 am 10:19 AM

How to use the LIKE operator for pattern matching in SQL?

The LIKE operator in SQL is used to search for patterns in string data, and is often used for inaccurate matching. The main usage scenarios include: 1. Find strings starting with specific characters, such as LIKE'J%' matching "John", "Jane", etc.; 2. Match content containing specific substrings, such as LIKE'%book%' matching "Notebook", "Textbook", etc.; 3. Match single characters with underscores, such as LIKE'A_3' matching "AB3", "AC3", etc.; 4. Combine wildcards to implement complex patterns,

Aug 08, 2025 am 10:14 AM