WGU D426 Database Applications – 100+ Solved Q&As | ERD, SQL Joins, Indexing, Normalization, Keys & Hashing | 2025/2026 | Western Governors University

This D426 Study Guide for Database Applications at Western Governors University includes over 100 verified and explained Q&As, specifically aligned with the 2025/2026 curriculum. Covering both theoretical design and practical application of databases, this guide helps students prepare for WGU's performance-based assessments in relational modeling, normalization, indexing, and SQL operations. The content addresses critical areas such as: Entity-Relationship Modeling: ER diagrams, relationships, attributes, weak entities, supertype/subtype (IsA) relationships, symbols, and subject areas SQL & Query Logic: INNER JOIN, CROSS JOIN, aggregation functions (e.g., MIN), TRUNCATE, INSERT, comparison operators, and query correlation Database Design & Keys: primary key, foreign key, composite key, candidate key, artificial key, simple key, and junction table relationships Normalization & Dependencies: 1NF, 3NF, BCNF, trivial dependency, functional dependency, table merging (denormalization), redundancy control Indexing & Optimization: dense index, hash index, bitmap index, fan-out, branch paths, physical vs. logical index structures Partitioning & Sharding: table partitions, shards, horizontal partitioning, data subsets across distributed systems Architecture & Storage: storage engine, tablespace, cluster, node, federated and distributed databases, multi-tier systems Data Modeling Phases: conceptual, logical, and physical design; analysis vs. implementation steps Mathematical Tools & Logic: modulo function, transfer rate, hash tables, binary search, set notation Perfect for flashcard-based learning or targeted revision, this guide empowers students to build a deep and applicable understanding of database concepts across both design and execution layers. Best suited for: WGU students enrolled in D426: Database Applications Learners in information systems, software development, or data analytics SQL practitioners and database administrators prepping for exams or certification Instructors and peer tutors delivering database logic and structure coursework Keywords: WGU D426, database applications, ER diagram, functional dependency, candidate key, foreign key, SQL joins, normalization, BCNF, bitmap index, partitioning, sharding, federated database, distributed database, logical design, storage engine, multi-tier architecture, relational schema, junction table, SQL query structure, hash table, DDL, set notation