SQL - UNIQUE Constraint
• UNIQUE constraints prevent duplicate values in columns while allowing NULL values (unlike PRIMARY KEY), making them essential for enforcing business rules on alternate keys like email addresses,…
Read more →Constraint
SQL - PRIMARY KEY Constraint
• PRIMARY KEY constraints enforce uniqueness and non-null values on one or more columns, serving as the fundamental mechanism for row identification in relational databases
Read more →SQL - NOT NULL Constraint
The NOT NULL constraint ensures a column cannot contain NULL values. Unlike other constraints that validate relationships or value ranges, NOT NULL addresses the fundamental question: must this field…
Read more →SQL - FOREIGN KEY Constraint
A foreign key constraint establishes a link between two tables by ensuring that values in one table’s column(s) match values in another table’s primary key or unique constraint. This relationship…
Read more →SQL - DEFAULT Constraint
• DEFAULT constraints provide automatic fallback values when INSERT or UPDATE statements omit column values, reducing application-side logic and ensuring data consistency
Read more →SQL - CHECK Constraint
CHECK constraints define business rules directly in the database schema by specifying conditions that column values must satisfy. Unlike foreign key constraints that reference other tables, CHECK…
Read more →Backtracking: Constraint Satisfaction Problems
Constraint Satisfaction Problems represent a class of computational challenges where you need to assign values to variables while respecting a set of rules. Every CSP consists of three components:
Read more →