MySQL?? ?????? ???? ??? ??????
AdbasetSupandConfiguresMysqlinStances? ?? ???, StorageEngines ? ConfigurationParametersTopReverformanceSues.2
Sep 05, 2025 am 04:12 AM
MySQL ?? ???? : ?? ? ???
MySQL ?? ????? ??? ??? ??? ??? ???? ?? ??? ??? ???? ????. 1. ???? ??? Sysbench (OLTP ???? ???? ??), MySQLSLAP (Lightweight Formal Tool), HammerDB (??? ?????? ?? ???) ? JMeter (Flexible Database Stress Testing); 2. ??? ??? ??? ????? ?? ??? ???? ?? ???? ???? ??? ???? ???? ???????. 3. QPS/TPS, ?? ??, ?? ?? ? ???? ?? ?? ?????? ?????. 4. ??? ??? ??? ??? ???? ???? ???? ???? ???? ????, ?? ???? ????, ?? ? ???? ????, ?? ???? ?? ???? ??????.
Sep 05, 2025 am 02:27 AM
MySQL?? Rank () ? Dense_Rank ()? ???? ??
MySQL? ?? 8.0 ?? rank () ? dense_rank () ? ??? ????? ?? ????? ???? ?????. 1. rank ()? ?? ?? ? ??? ??? ????? ?? ??? ??? ????. 2. Dense_Rank ()? ?? ?? ? ???? ??? ??? ???? ??? ????. 3. PartitionBy? ?? ???? ?? ? ? ????. MySQL8.0 ??? ??? ?? ?? ?????? ?????. ??? ??? ?? ?? ??????? ?? ????. selectVersion ()? ???? ??? ???? ? ?? ??? ???? ????? ??????.
Sep 05, 2025 am 01:41 AM
MySQL?? ?? ??? ???? ??
?? ()? ?? ??? ??? ????, ?? ?? ??? ??? ??? ???? ???? ? ?????. 1. SelectNow ()? ?? ?? ?? ???? ?? ?? ?? select?? ?? ??? ? ????. 2. ????? ?? ??? ???? ???? ?? ??? ???? ?? DefaultNow () ??? ?????. 3. OnupDatenow ()? ?? ? ?????? ??? ???? ?????? ?????. 4. ?? ??? ???? ()? ?? ??? ??? ????, curdate ()? ??? ????, curtime ()? ??? ???? UTC_TIMESTAMP ()? UTC ??? ?????. ??? ??? ? ?? ??? datetime ?? timestamp?? ???? ?????.
Sep 04, 2025 am 08:51 AM
MySQL?? ?? ?? ???? ???? ??? ??????
insertignoreInMysqLallowsInsertingRowsWhileStrowsIllentySkippingErrorslikingErorslikedupliceKeysorInvalidData, duplicates.1) useIttoInyifitdoes to notelakeifitdoes to notaledoxistbasedonUnunUniqueRprimaryConstrAnts.2) it
Sep 04, 2025 am 08:23 AM
MySQL?? ON ?? ? ???? ?? ??? ??????
theonduplicatekeyupdatestatementinmysqlallowsaninsertoperationtoupdateanexistingrowifaduplicatuprimarykeysfound, efficientupserts? ?? ? ????
Sep 04, 2025 am 08:21 AM
MySQL?? ?? ? ???? ??? ??????
TheDISTINCTkeywordinMySQLremovesduplicaterowsfromqueryresults,returningonlyuniquevaluesbasedontheselectedcolumns;itworksbytreatingrowsasduplicatesonlyifallselectedcolumnvaluesareidentical,includingNULLsasequal,andisappliedtosinglecolumnstoeliminatere
Sep 04, 2025 am 07:15 AM
MySQL?? ?? ??? ???? ??
curtime () returnsthecurrenttimeinhh : mm : ssformatwithoutThedate; 1.useSelectCurtime () TOGETECURRENTSYSTEMTIME; 2. includePrecisionArgumentlikeCurtime (3) ForfractionEcondSuptomicroseconds; 3.insertcurtimecolecolecolecolecolecolecolecodecolecordecodecodecordecordecodecordecord.;
Sep 04, 2025 am 06:51 AM
MySQL?? NULL ?? ???? ??? ??????
useNullOrisnultNullTocheckFornUllValuesBECAUSESTANDARDERCOMPARISONSWITH = ??! = ret???
Sep 04, 2025 am 06:47 AM
MySQL?? ???? ??? ??
MySQL ???? ?? ???? ?? ??? ??? ???? ????? CreateUser? ???? ??? ??, ??? ? ????? ??? ?? Grant ?? ?? ?? ??? ???? ????? FlushPrivileges? ???? ?????. MySQL : MySQL-Uroot-P; 2. ??? ??? : CreateUser'Username '@'host'IndifiedBy'Password '; 3. ??? ?? : grantprivilege_typeondatabase_name.table_nameto'username'@'host '; 4. ??? ?? : ??
Sep 04, 2025 am 02:42 AM
MySQL?? ??????? ???? ??
USETHEUSEDATABASE_NAME; COMMANDABASE_NAME, COMMANDECTADATABASEINMYSQL, ?? DATABASE_NAMEWITHTHEDERDEDDATABASE.2.listAvailableABaseSwithShowDatabaseSHOWDATABASES.3
Sep 04, 2025 am 12:06 AM
MySQL?? ???? ??? ?? ???? ???? ??
TOCONVERTRINGTOUPPERCAYORLOWERCASEINMYSQL, USETHEUPPER () andLOWER () functions.1.USEUPPER (str) TOCONVERTRINGTOUPPERCASE (? : SELECTUPPER ( 'hellowORLD') returnShellowld, OrApplyIttoOlumnLikeSelectUpper (OrapPlyIttoOlumnlikeSelectupper)
Sep 03, 2025 am 07:01 AM
MySQL? ??? ??? ??? ??????
OptimizetableIsusedToreOrganizephysicalStorageAndeAmunuedSpacate ateRlaGedELETIONSORUPDATES, ?? ininnodbandmyisAmtables; itrebuildSthetableByCopyingAnlylaTATA, DEFRAGSTORAGE, ???? indexStatics, reseto-incrementcountersomeca
Sep 03, 2025 am 05:54 AM
??? ?? MySQL ?? ??? ????? ??
setInnodb_buffer_pool_sizeto70–80-80%ofram (? : 12Gon16gbram) ? ConconfigureInnodb_buffer_pool_instancesto1per1gbofbufferpool (? :, 8FOR12G); repykey_buffer_sizesmall (32–64m)? myiSamheavily? ???? ?? ?;
Sep 03, 2025 am 05:04 AM
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