Lub ntsiab yam ntawm Mysql cov ntaub ntawv

Rau cov neeg uas tsis paub dab tsi Mysql, qhia rau koj hais tias qhov no yog ib tug zoo heev system uas tso cai rau koj los tswj loj nyiaj ntawm cov ntaub ntawv. Nws yog pub dawb thiab muaj rau cov neeg siv rau lub tej yam kev mob ntawm lub dav daim ntawv tso cai. Thaum qhov kaj ntug ntawm computer technology "warehoused" cov ntaub ntawv mus rau hauv nyias muaj nyias ib cov ntaub ntawv, thiab ces muab tshem tawm nws los ntawm lawv raws li tsim nyog. Niaj hnub no, cov tshuab tsis yeej ib txwm zoo, vim hais tias cov nws yuav siv sij hawm ib tug ntau lub sij hawm thiab kev rau siab. Mysql software cia koj xaiv cov ntaub ntawv thiab kev khiav hauj lwm nyob rau hauv arrays ntawm cov ntaub ntawv los ntawm txoj kev ntawm ib tug heev compact hais kom code.

Nyob rau hauv kev txiav txim rau lub database mus ua hauj lwm kom zoo, yog ib lub tswvyim nyob rau hauv lub Mysql cov ntaub ntawv hom. Tag nrho cov uas tau txheeb xyuas ib tug xov tooj ntawm cov kev xaiv:

- VAR (n) los yog VARCHAR (n) - cim, qhov twg n - lub xov tooj ntawm bytes uas yuav siv tau (VARCHAR khw muag khoom noj tsis muaj ntau tshaj li 255 cim);

- txoj hlua ntaub ntawv hom mysql, kuj muaj cov nram qab no hom: NTAWV (n) - nyob qhov twg n can yuav mus txog 65,535, TINITEXT (n) - nyob qhov twg n Tej zaum yuav muaj ib tug nqi mus txog 255, MEDIUMTEXT (n) nrog n 16 777 215 thiab LONGTEXT ( n) lub nce mus nce los n, uas yuav ncav cuag 4294967295 (los ntawm VARCHAR nce mus nce los NTAWV yus nyob rau hauv hais tias rau NTAWV (n) indexed thawj n cim);

- VARBINARY los yog Binary - mus cia dluab nyob rau hauv binary code ;

- mus cia binary loj khoom rhiab cim siv cov ntaub ntawv hom Mysql blob (n), uas muaj tib lub dimension thiab "prefix", raws li NTAWV (TINY-, MEDIUM-, LONGBLOB) ; piv txwv li, MEDIUMBLOB (n) muaj lub dimension n sib npaug zos rau 16.777.215;

- cov ntaub ntawv hom rau hnub thiab lub sij hawm, xws li: HNUB TIM - ib hnub nyob rau hauv cov hom ntawv xyoo-hli-hnub, lub SIJ HAWM - lub sij hawm nyob rau hauv hom ntawv teev-feeb-thib ob, cov XYOO - lub xyoo los ntawm 1901 mus 2155 thiab lub xyoo 0000, ib tug DateTime - combines HNUB thiab SIJHAWM (lub xeem hom ntawm cov ntaub ntawv tso tawm nyob rau hauv lub hom xyoo-hli-hnub-teev-feeb-thib ob); muaj tseem yog cov Mysql cov ntaub ntawv format rau timestamp, uas tso cai rau koj los mus ua kom cov database rau hauv lub xyoo ntawm xyoo 1970 rau 2037 (qhov no yog tshwm sim los ntawm cov assumption ntawm lub system creators uas Mysql kiag li lawm los ntawm 2037);

- numeric, uas nyob rau hauv nws cov muaj pes tsawg leeg muaj integer cov ntaub ntawv hom, xws li - cov menyuam - integer los txog 2.1 billion rau $ 2.1 billion rho tawm, TINYINT - .. Ib tug xov tooj ntawm 128 rau 255, los yog los ntawm -127 rau 0, SMALINT - 768 rau 32 - 32 767, BIGINT - 9 x 10 -9 rau xyoo degree x 10 degree nyob rau hauv lub xyoo, MEDIUMINT - .. ntawm 8,388 plhom los -8,388 lab (tshwj tsis yog tias nyob rau hauv ib qho kev hom ntawm cov ntaub ntawv teev xov tooj loj lub siab tshaj plaws set nqi, nws yuav tsum tau truncated rau siv tau qhov tseem ceeb).

Tseem muaj hom fractional zauv - Ntab - yog ib tug floating taw tes tooj, OB thiab tiag - ob chav hauv lub xov tooj ntawm floating taw tes ceev, numeric thiab zauv - fractional tus xov tooj yog muab ua cov hlua. Cov programming yog feem ntau siv ntab thiab cov menyuam, uas txhawb puag ua hauj lwm pom ceev.

Ua hauj lwm nrog database los ntawm phpmyadmin cuab tam, uas los pub nyob rau hauv Denver pob. Nrog nws koj muaj peev xwm tsim ib tug database, specifying lub npe ntawm database ntxhuav thiab ntau hom ntawm cov ntaub ntawv, passwords. Ces tus puag yog lawm ua tus sau nrog cov lus qhia, nws tseem tau los ua ib tug kev tshawb fawb thov (xaiv), kev hloov (CHANGE, rename, hloov), deletion (RHO TAWM), ntxiv (NTXIV) los yog sorting cov muaj ntaub ntawv thiab tso zis tsis txhais ntawm qhov screen. Mysql cov ntaub ntawv hom nyob rau hauv cov ntaub ntawv no yuav tsum tau ntxiv kom zoo zoo heev rau qhov kev pab cuam yog hais tsis tau muab uas tsis. Piv txwv li, koj yuav hais kom meej lub hom ntawm cov ntaub ntawv rau ib tug VARCHAR, uas tso cai rau cov kev taw qhia ntawm cov ntawv nyeem nyob rau hauv lub database tsis muaj ntau tshaj li 255 cim. Thiab thaum sau tus puag ntawv nyeem yuav tsum ntau ntau, uas yuav ua rau lub fact tias cov Mysql "truncate" cov ntawv nyeem rau ib tug siv tau ntev.