Informal guidelines are practical rules used to design high-quality relational schemas that minimize redundancy, avoid anomalies, and ensure data consistency. These guidelines are not strictly based on normal forms, but they help in achieving a good design. 1. Avoid Redundant…
Normalization in DBMS Normalization is a process in database design used to: Normalization involves breaking a database into smaller, well-structured tables using normal forms. 1. First Normal Form (1NF) Rule: Example (Unnormalized Table): RollNo Name Subjects 101 Arun Math, Physics…
Cursor in Embedded SQL A cursor in embedded SQL is a pointer that allows you to retrieve and process one row at a time from the result of a query. It is mainly used in procedural languages like C, Java,…
Unary Relational Operations in Relational Algebra Unary operations are operations that are applied to a single relation (table). These are used to filter or manipulate data from one table without involving another relation. 1. SELECT (σ) — Selection Definition: Syntax:…
E-R to Relational Mapping Algorithm (Step-by-Step with Examples) The E-R to Relational Mapping Algorithm converts an Entity-Relationship (ER) diagram into a Relational Schema (set of tables). This is essential to implement a database design in SQL. There are six main…
Relational algebra includes set theory operations because relations (tables) are treated as sets of tuples (rows). These operations work on two relations that are union-compatible (i.e., same number of columns and same data types). Here is a clear explanation of…
Discuss Equijoin & Natural Join with examples. Answer:- 1. Equi Join Definition: Example: Assume we have the following tables: Query using Equi Join: Key Point: 2. Natural Join Definition: Example: Using the same tables: Key Point: Comparison Table Feature Equi…
Write SQL queries for Sailors-Boats-Reserves database: 1. Find colors of boats reserved by Alber. 2. Sailor IDs with rating ≥ 8 or who reserved boat 103. 3. Sailor names who didn’t reserve boat containing “storm”. 4. Sailor IDs over age 20 who didn’t reserve…
Explain Entity Integrity Constraint & Referential Integrity Constraints. Why is each important in a database? Answer:- 1. Entity Integrity Constraint Definition: The Entity Integrity Constraint states that: Why It’s Important: Example: 2. Referential Integrity Constraint Definition: The Referential Integrity Constraint…
Explain different update operations on relational databases. How do basic operations deal with constraint violation? Update Operations in Relational Databases In a relational database, update operations are used to modify the data in tables. These include: 1. Insert Example: 2.…
