DDL yog Data Definition Language uas yog siv los txhais cov qauv ntaub ntawv. Piv txwv li: tsim rooj, hloov rooj yog cov lus qhia hauv SQL. DML: DML yog Data Manipulation Language uas yog siv los tswj cov ntaub ntawv nws tus kheej. Piv txwv li: ntxig, hloov tshiab, rho tawm yog cov lus qhia hauv SQL.
DDL nqe lus yog dab tsi?
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. Feem ntau Impala DDL nqe lus pib nrog cov ntsiab lus CREATE, DROP, lossis ALTER.
DDL DML thiab DCL yog dab tsi?
DDL – Cov ntaub ntawv txhais lus. DQl – Cov ntaub ntawv nug lus. DML – Data Manipulation Language . DCL – Data Control Language.
DDL piv txwv yog dab tsi?
Stands for "Data Definition Language." A DDL yog ib hom lus siv los txhais cov qauv ntaub ntawv thiab hloov kho cov ntaub ntawv. Piv txwv li, DDL cov lus txib tuaj yeem siv los ntxiv, tshem tawm, lossis hloov cov ntxhuav hauv cov ntaub ntawv. … Yog tias lub rooj tsis xav tau lawm, DROP hais kom ua yuav raug siv los tshem tawm lub rooj.
DML sawv cev rau dab tsi?
A data manipulation language (DML) yog lub khoos phis tawj programming lus siv los ntxiv (ntxig), tshem tawm, thiab hloov kho (hloov kho) cov ntaub ntawv hauv cov ntaub ntawv. DML feem ntau yog ib hom lus ntawm cov lus dav dav xws li SQL,nrog DML suav nrog qee tus neeg ua haujlwm hauv hom lus.
