Nepal Oil Corporation2078 BSQuestion 4 of 5

Explain about the basic concepts of Records, Relationships, Indexing and Keys with respect to Database Management System.

10 marks

Model answer

Four pillars of a clean NOC fuel DB (consistent terminology across papers).

Record (row): One complete entry — e.g. (D01, Petrol, 5000L, 2078-09-22) in Stock table. Fields = columns (DepotID, Fuel, Qty).
Relationships (PK → FK links): 1:M — one Depot has many Stock rows (Depot.DepotID PK → Stock.DepotID FK); M:N via junction (Dealers ↔ Fuels through Supply); 1:1 — Depot ↔ DepotSecurity split for restricted access. Enforced in Access Relationships with referential integrity.
Indexing: Fast-lookup structure like book index on frequent fields (DepotID, Date). Speeds search/sort/join; unique index enforces no duplicates. Cost: slight insert overhead — index only searched fields.
Keys: Primary (unique, never NULL, one per table — DepotID), Foreign (link to parent PK — Stock.DepotID), Candidate/Composite as needed. Together they guarantee identity + linkage.

Nepal Oil Corporation2078 BSQuestion 4 of 5

10 marks

Four pillars of a clean NOC fuel DB (consistent terminology across papers).

Record (row): One complete entry — e.g. (D01, Petrol, 5000L, 2078-09-22) in Stock table. Fields = columns (DepotID, Fuel, Qty).
Relationships (PK → FK links): 1:M — one Depot has many Stock rows (Depot.DepotID PK → Stock.DepotID FK); M:N via junction (Dealers ↔ Fuels through Supply); 1:1 — Depot ↔ DepotSecurity split for restricted access. Enforced in Access Relationships with referential integrity.
Indexing: Fast-lookup structure like book index on frequent fields (DepotID, Date). Speeds search/sort/join; unique index enforces no duplicates. Cost: slight insert overhead — index only searched fields.
Keys: Primary (unique, never NULL, one per table — DepotID), Foreign (link to parent PK — Stock.DepotID), Candidate/Composite as needed. Together they guarantee identity + linkage.