99久久国产综合精品swag,japanesexxxx日本熟妇伦

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

Mysql Tutorial

What is the role of the database administrator in MySQL?

ADBAsetsupandconfiguresMySQLinstanceswithoptimalversions,storageengines,andconfigurationparameterstopreventperformanceissues.2.Theymanageuseraccessandsecuritybycreatingaccounts,assigningprivileges,enforcingpasswordpolicies,andmonitoringforunauthorize

Sep 05, 2025 am 04:12 AM

mysql 數(shù)據(jù)庫管理員

Benchmarking MySQL Performance: Tools and Methodologies

The key to MySQL performance benchmarking is to select the right tools and methods and develop scientific testing plans. 1. Common tools include sysbench (suitable for OLTP stress testing), mysqlslap (lightweight official tool), HammerDB (graphical enterprise-level testing) and JMeter (flexible database stress testing); 2. The test plan needs to clarify the goals, set parameters, use real data, and control variables to ensure accuracy; 3. Pay attention to core indicators such as QPS/TPS, response time, resource usage, and error rate; 4. The test environment should be close to production, maintain hardware consistency, network stability, shut down interfering services, multiple runs to average, and avoid direct testing in the production environment.

Sep 05, 2025 am 02:27 AM

How to use RANK() and DENSE_RANK() in MySQL

MySQL supports RANK() and DENSE_RANK() window functions since version 8.0, but was not supported in the previous version. 1. RANK() gives the same ranking when the values ??are equal, but subsequent rankings create gaps; 2. DENSE_RANK() ranks the same when the values ??are equal and there is no gaps in the future; 3. You can sort by group through PARTITIONBY; for versions below MySQL8.0, variable simulation is required. It is recommended to upgrade to obtain complete support. Use SELECTVERSION() to check the version to ensure that the window function function is correctly applied.

Sep 05, 2025 am 01:41 AM

How to use the NOW function in MySQL

NOW() returns the current date and time, which is often used to record the exact moments of data operations; 1. It can be used directly in SELECT, such as SELECTNOW() to get the current timestamp; 2. Automatically record the creation time in INSERT, and supports setting DEFAULTNOW() to achieve automatic filling; 3. Automatically update and modify time in UPDATE combined with ONUPDATENOW(); 4. Compared with other functions, NOW() returns the local date and time, CURDATE() returns the date, CURTIME() returns the time, and UTC_TIMESTAMP() returns the UTC time; when using it, make sure that the field type is DATETIME or TIMESTAMP, and it is recommended to

Sep 04, 2025 am 08:51 AM

mysql now function

How to use the INSERT IGNORE statement in MySQL?

INSERTIGNOREinMySQLallowsinsertingrowswhilesilentlyskippingerrorslikeduplicatekeysorinvaliddata,makingitidealforensuringrecordsexistwithoutduplicates.1)Useitwhenyouwanttoinsertarowonlyifitdoesn’talreadyexistbasedonuniqueorprimarykeyconstraints.2)Itpr

Sep 04, 2025 am 08:23 AM

What is the purpose of the ON DUPLICATE KEY UPDATE statement in MySQL?

TheONDUPLICATEKEYUPDATEstatementinMySQLallowsanINSERToperationtoupdateanexistingrowifaduplicateuniqueorprimarykeyisfound,avoidingerrorsandenablingefficientupserts;whenaduplicateisdetected,thespecifiedcolumnsareupdatedusingtheVALUES()functiontoreferen

Sep 04, 2025 am 08:21 AM

What is the purpose of the DISTINCT keyword in MySQL?

TheDISTINCTkeywordinMySQLremovesduplicaterowsfromqueryresults,returningonlyuniquevaluesbasedontheselectedcolumns;itworksbytreatingrowsasduplicatesonlyifallselectedcolumnvaluesareidentical,includingNULLsasequal,andisappliedtosinglecolumnstoeliminatere

Sep 04, 2025 am 07:15 AM

How to use the CURTIME function in MySQL

CURTIME()returnsthecurrenttimeinHH:MM:SSformatwithoutthedate;1.UseSELECTCURTIME()togetthecurrentsystemtime;2.IncludeaprecisionargumentlikeCURTIME(3)forfractionalsecondsuptomicroseconds;3.InsertCURTIME()intoTIMEtypecolumnstorecordstarttimes;4.Useitinf

Sep 04, 2025 am 06:51 AM

How to handle NULL values in MySQL?

UseISNULLorISNOTNULLtocheckforNULLvaluesbecausestandardcomparisonswith=or!=returnunknown;2.ApplyCOALESCE()orIFNULL()toreplaceNULLswithdefaultvaluesinresults;3.WrapnullablecolumnsinfunctionslikeCOALESCE()duringarithmetictopreventNULLoutcomes;4.Enforce

Sep 04, 2025 am 06:47 AM

mysql null value

How to create a user in MySQL

Create a MySQL user first, first use the administrator account to log in, execute CREATEUSER to specify the user name, host and password, then give the corresponding permissions through the GRANT statement, and finally run FLUSHPRIVILEGES to take effect, 1. Connect to MySQL: mysql-uroot-p; 2. Create a user: CREATEUSER'username'@'host'IDENTIFIEDBY'password'; 3. Grant permissions: GRANTprivilege_typeONdatabase_name.table_nameTO'username'@'host'; 4. Refresh permissions: FLU

Sep 04, 2025 am 02:42 AM

How to select a database in MySQL

UsetheUSEdatabase_name;commandtoselectadatabaseinMySQL,replacingdatabase_namewiththedesireddatabase.2.ListavailabledatabaseswithSHOWDATABASES;ifunsurewhichonesexist.3.VerifythecurrentlyselecteddatabaseusingSELECTDATABASE();whichreturnstheactivedataba

Sep 04, 2025 am 12:06 AM

How to convert a string to uppercase or lowercase in MySQL

ToconvertastringtouppercaseorlowercaseinMySQL,usetheUPPER()andLOWER()functions.1.UseUPPER(str)toconvertastringtouppercase,e.g.,SELECTUPPER('helloworld')returnsHELLOWORLD,orapplyittoacolumnlikeSELECTUPPER(name)FROMusers.2.UseLOWER(str)toconvertastring

Sep 03, 2025 am 07:01 AM

mysql String conversion

What is the OPTIMIZE TABLE command in MySQL?

OPTIMIZETABLEisusedtoreorganizephysicalstorageandreclaimunusedspaceafterlargedeletionsorupdates,particularlyinInnoDBandMyISAMtables;itrebuildsthetablebycopyingonlylivedata,defragmentsstorage,updatesindexstatistics,resetsauto-incrementcountersinsomeca

Sep 03, 2025 am 05:54 AM

How to optimize the MySQL server configuration for performance

Setinnodb_buffer_pool_sizeto70–80%ofRAM(e.g.,12Gon16GBRAM)andconfigureinnodb_buffer_pool_instancesto1per1GBofbufferpool(e.g.,8for12G);keepkey_buffer_sizesmall(32–64M)unlessusingMyISAMheavily;increasetmp_table_sizeandmax_heap_table_sizeto256Mifdisk-ba

Sep 03, 2025 am 05:04 AM

performance mysql optimization