Dab tsi yog kev sib tshuam hauv kev sib raug zoo algebra?

2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47

INTERSECTION Kev ua haujlwm hauv RELATIONAL ALGEBRA . Kev sib tshuam ntawm teeb A thiab B = A ∩ B = {1, 6} Cov ntsiab lus uas muaj nyob rau hauv ob qho tib si A thiab B yuav tsuas muaj nyob rau hauv lub teeb tau los ntawm kev sib tshuam ntawm A thiab B.

Tib neeg kuj nug, dab tsi yog kev sib raug zoo algebra qhia?

Relational Algebra . Relational algebra yog ib tug txheej txheem query lus, uas yuav siv sij hawm ntawm kev sib raug zoo raws li cov tswv yim thiab yields piv txwv ntawm kev sib raug zoo raws li tso zis. Nws siv cov neeg ua haujlwm los ua cov lus nug. Relational algebra yog ua recursively ntawm kev sib raug zoo thiab cov txiaj ntsig nruab nrab kuj suav tias yog kev sib raug zoo.

Ib sab saum toj no, kev sib tshuam hauv DBMS yog dab tsi? Cov INTERSECT tus neeg teb xov tooj yog siv los ua ke zoo li kab los ntawm ob cov lus nug. Nws rov qab cov kab uas zoo sib xws ntawm ob qhov txiaj ntsig. Yuav siv lub INTERSECT tus neeg teb xov tooj, ob qho lus nug yuav tsum rov qab tib cov kab ke thiab cov kab ntawv yuav tsum yog cov ntaub ntawv sib xws.

Cov lus nug tseem yog, qhov piv txwv ntawm kev sib txheeb algebra yog dab tsi?

Relational algebra mas muab theoretical foundation rau kev sib raug zoo databases thiab SQL. Cov neeg ua haujlwm hauv Relational Algebra . Projection (π) Projection yog siv los tsim cov ntaub ntawv xav tau ntawm kab ntawv los ntawm kev sib raug zoo. Piv txwv : R (A B C) ---------- 1 2 4 2 2 3 3 2 3 4 3 4 π (BC) B C ----- 2 4 2 3 3 4.

Dab tsi yog qhov kev siv ntawm kev sib raug zoo algebra hauv DBMS?

Relational algebra yog dav siv txheej txheem lus nug. Nws sau cov xwm txheej ntawm kev sib raug zoo raws li kev tawm tswv yim thiab muab qhov tshwm sim ntawm kev sib raug zoo raws li cov zis. Nws siv ntau yam haujlwm los ua qhov haujlwm no. Relational algebra kev khiav hauj lwm yog ua recursively ntawm kev sib raug zoo.