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INFO MANAGEMNET L7

Database Normalization​ and Design​

QuestionAnswer
A table stores data in rows (records) and columns (attributes)​ Database Table
process of evaluating and correcting table structures to minimize data redundancies.​ Works through a series of stages called Normal Forms (NF)​ Normalization
is the process of breaking big, messy tables into smaller, well-organized tables.​ ​Normalization
Each table represents a single subject; one table should focus on one real-world entity only​ No data item should be unnecessarily stored in more than one table Key Principles of Normalization
cannot add data because other data is missing​ Insertion anomaly
must update the same data in multiple rows​ Update anomaly
deleting data accidentally removes important information​ Deletion anomaly
No repeating groups. Each field contains atomic (single) values First Normal Form (1NF)
Must be in 1NF All non-key attributes must depend on the entire primary key Second Normal Form (2NF)
Must be in 2NF, No transitive dependency Third Normal Form (3NF)
unique, never null, rarely change Evaluate Primary Key (PK) Assignments
clear, consistent, and meaningful names for Tables and Columns. Evaluate Naming Conventions
each column should store only one piece of information. Refine Attribute Atomicity
design for current needs, but be mindful of future growth. Identify New Attributes
look for hidden relationships between tables Identify New Relationships
databases should tell the story of the past, not just the present. Maintain Historical Accuracy
values that can be calculated from other data (age, total). Evaluate using Derived Attributes
If a table does more than one job, split it One table is for one main purpose
System-generated key (id, _id, objectId) Has no real-world meaning Surrogate Key Considerations
Stricter version of 3NF BCNF
handle complex multi-valued dependencies 4NF / 5NF
Joining the larger number of tables reduces system speed. Denormalization
Created by: user-1782765
 

 



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