Tsab ntawv teev npe
MySQLCov ntaub ntawv txhawb nqa yog dab tsi?MySQLCov ntsiab lus ntawm cov ntaub ntawv hom hauv
MySQL cov ntaub ntawv hom
Cov hom ntaub ntawv teev tseg hauv MySQL tseem ceeb heev rau kev ua kom zoo ntawm koj cov ntaub ntawv.
MySQL txhawb ntau hom, uas tuaj yeem muab faib ua peb pawg: tus lej, hnub / sijhawm, thiab hlua (tus cwj pwm) hom.
Hom lej
MySQL databaseTxhua tus qauv SQL tus lej cov ntaub ntawv tau txais kev txhawb nqa.
Cov hom no suav nrog cov ntaub ntawv xov xwm nruj (INTEGER, SMALLINT, DECIMAL, thiab NUMERIC), thiab kwv yees cov ntaub ntawv hom (FLOAT, REAL, thiab DOUBLE PRECISION).
Lo lus tseem ceeb INT yog lub ntsiab lus rau INTEGER thiab lo lus tseem ceeb DEC yog lub ntsiab lus rau DECIMAL.
Cov ntaub ntawv BIT tuav cov nqi me ntsis thiab txhawb nqa MyISAM, MEMORY, InnoDB, thiab BDB cov lus.
Raws li kev txuas ntxiv rau tus qauv SQL, MySQL kuj tseem txhawb nqa cov lej suav TINYINT, MEDIUMINT, thiab BIGINT.Cov lus hauv qab no qhia txog kev khaws cia thiab ntau yam uas xav tau rau txhua hom integer.
| Hom | qhov loj me | ntau yam (kos npe) | ntau yam (tsis tau kos npe) | Siv |
|---|---|---|---|---|
| TINYINT | 1 byte ib | (—128, 127) | (0 hli) | tus nqi me me |
| ME | 2 byte ib | (-32 768, 32 767) | (0, 65) | loj integer tus nqi |
| MEDIUM | 3 byte ib | (-8 388 608, 8 388 607) | (0, 16 777 215) | loj integer tus nqi |
| INT los yog INTEGER | 4 byte ib | (-2 147 483 648, 2 147 483 647) | (0, 4 294 967 295) | loj integer tus nqi |
| BIGINT | 8 byte ib | (-9 233 372 036 854 775 808, 9 223 372 036 854 775 807) | (0, 18 446 744 073 709 551 615) | tus nqi integer loj heev |
| Ntab | 4 byte ib | (-3.402 823 466 E+38, -1.175 494 351 E-38), 0, (1.175 494 351 E-38, 3.402 823 466 351 E+38) | 0, (1.175 494 351 E-38, 3.402 823 466 E+38) | ib precision floating point tus nqi |
| OB | 8 byte ib | (-1.797 693 134 862 315 7 E+308, -2.225 073 858 507 201 4 E-308), 0, (2.225 073 858 507 201 4 E-308, 1.797 693, 134, 862, 315, | 0, (2.225 073 858 507 201 4 E-308, 1.797 693 134 862 315 7 E + 308) | dual precision floating point tus nqi |
| NKAUJ NTSEEG | Rau DECIMAL (M, D), yog M> D, nws yog M + 2 nws yog D + 2 | nyob ntawm qhov tseem ceeb ntawm M thiab D | nyob ntawm qhov tseem ceeb ntawm M thiab D | tus nqi decimal |
hom hnub thiab sijhawm
Hnub thiab sijhawm hom uas sawv cev rau lub sijhawm muaj nuj nqis yog DATETIME, DATE, TIMESTAMP, TIME, thiab YEAR.
Txhua lub sij hawm hom muaj ntau yam khoom siv tau thiab tus nqi "zero", uas yog siv thaum qhia txog tus nqi tsis raug uas MySQL tsis tuaj yeem sawv cev.
Hom TIMESTAMP muaj qhov muaj tswv yim hloov kho nws tus kheej uas yuav piav qhia tom qab.
| Hom | qhov loj me (byte) | khwv | hom | Siv |
|---|---|---|---|---|
| HNUB TIM | 3 | 1000-01-01/9999-12-31 | YYYY-MM-DD | hnub tus nqi |
| SIJHAWM | 3 | ‘-838:59:59'/'838:59:59' | HH: HLI: SS | lub sijhawm tus nqi lossis lub sijhawm |
| Xyoo | 1 | 1901/2155 | YYYY | xyoo tus nqi |
| Teev Ntuj | 8 | 1000-01-01 00:00:00/9999-12-31 23:59:59 | XYOO-MM-DD HH: HLI: SS | Cov hnub tim thiab lub sijhawm sib xyaw |
| TIMESTAMP | 4 | 1970-01-01 00:00:00/2037 年某时 | YYYYMMDDHHMMSS | sib xyaw hnub thiab lub sijhawm muaj nuj nqis, timestamp |
Hom hlua
Cov hlua hom xa mus rau CHAR, VARCHAR, BINARY, VARBINARY, BLOB, TEXT, ENUM, thiab SET.Tshooj lus no piav qhia seb hom no ua haujlwm li cas thiab siv lawv li cas hauv cov lus nug.
| Hom | qhov loj me | Siv |
|---|---|---|
| TANK | 0-255 bytes | tsau-ntev hlua |
| LUB NTUJ CEEB TSHEEJ | 0-65535 bytes | variable length hlua |
| TINYBLOB | 0-255 bytes | binary hlua txog li 255 cim |
| TINYTEXT | 0-255 bytes | kab ntawv luv luv |
| Blob | 0-65 535 bytes | cov ntawv nyeem ntev hauv daim ntawv binary |
| TEXT | 0-65 535 bytes | cov ntaub ntawv ntev |
| MEDIUM BLOB | 0-16 777 215 bytes | Cov ntaub ntawv nruab nrab-ntev ntev hauv binary daim ntawv |
| MEDIUM TEXT | 0-16 777 215 bytes | cov ntaub ntawv ntev nruab nrab |
| LONGBLOB | 0-4 294 967 295 bytes | Cov ntaub ntawv loj heev hauv daim ntawv binary |
| LONGTEXT | 0-4 294 967 295 bytes | cov ntaub ntawv loj heev |
Hom CHAR thiab VARCHAR zoo sib xws, tab sis lawv tau khaws cia thiab rov qab sib txawv.Lawv kuj txawv nyob rau hauv cov nqe lus ntawm lawv qhov ntev tshaj plaws thiab seb qhov chaw trailing yog khaws cia.Tsis muaj cov ntaub ntawv hloov dua siab tshiab yog ua tiav thaum lub sijhawm khaws cia lossis rov qab.
Cov chav kawm BINARY thiab VARBINARY zoo ib yam li CHAR thiab VARCHAR, tshwj tsis yog tias lawv muaj cov hlua binary es tsis yog cov hlua sib txuas.Ntawd yog, lawv muaj cov hlua byte es tsis yog cov cim cov hlua.Qhov no txhais tau tias lawv tsis muaj tus cwj pwm teeb tsa, thiab kev txheeb xyuas thiab kev sib piv yog nyob ntawm tus lej ntawm cov nqi ntawm kab ntawv tus nqi bytes.
BLOB yog ib yam khoom loj binary uas tuaj yeem tuav cov ntaub ntawv sib txawv.Muaj 4 hom BLOB: TINYBLOB, BLOB, MEDIUMBLOB thiab LONGBLOB.Lawv tsuas yog txawv ntawm qhov ntev tshaj plaws ntawm tus nqi uas lawv tuaj yeem tuav tau.
Muaj 4 hom ntawv: TINYTEXT, TEXT, MEDIUMTEXT thiab LONGTEXT.Cov no sib raug rau 4 BLOB hom, nrog tib qhov ntev ntev thiab kev cia khoom.
Cia siab Chen Weiliang Blog ( https://www.chenweiliang.com/ ) qhia "Dab tsi yog cov ntaub ntawv hom txhawb nqa los ntawm MySQL? Kev piav qhia ntxaws txog cov ntaub ntawv hom hauv MySQL" los pab koj.
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