DDL yog hais txog Cov Lus Txhais Lus, ib pawg ntawm SQL nqe lus uas hloov cov qauv ntawm cov txheej txheem database hauv qee txoj kev, feem ntau los ntawm kev tsim, tshem tawm, lossis hloov kho cov khoom siv xws li raws li databases, rooj, thiab views.
piv txwv ntawm DDL nqe lus yog dab tsi?
DDL cov lus zoo ib yam li lub khoos phis tawj programming lus los txhais cov qauv ntaub ntawv, tshwj xeeb tshaj yog cov txheej txheem database. Piv txwv ntawm DDL nqe lus suav nrog CREATE, ALTER, thiab DROP.
DDL thiab DML nqe lus yog dab tsi?
DDL stands for Data Definition Language. … DDL nqe lus yog siv los tsim database, schema, txwv, cov neeg siv, rooj thiab lwm yam. DML nqe lus yog siv los ntxig, hloov kho lossis rho tawm cov ntaub ntawv.
nqe lus DML yog dab tsi?
DML ( Data Manipulation Language) cov lus yog cov ntsiab lus hauv SQL lus uas yog siv rau cov ntaub ntawv retrieval thiab manipulation. Siv cov nqe lus no koj tuaj yeem ua haujlwm xws li: ntxiv kab tshiab, hloov kho thiab tshem tawm kab uas twb muaj lawm, sib koom ua ke cov rooj thiab lwm yam.
DDL thiab DML nqe lus muab piv txwv yog dab tsi?
DDL yog Cov Lus Txhais Lus uas yog siv los txhais cov qauv ntaub ntawv. Piv txwv li: tsim lub rooj, hloov lub rooj yog cov lus qhia hauv SQL. DML: DML yog Data Manipulation Language uas yog siv los tswj cov ntaub ntawv nws tus kheej.
