4. Designing Effective Unique Constraints: NULL Considerations in MySQL
   A unique constraint in MySQL enforces that each value in a specified column (or set of columns) must be distinct within the table
5. Enforcing Unique Data Values Across Multiple Columns in SQLite
   SQLite is a lightweight, embedded relational database management system that's popular for its simplicity and efficiency
6. Maintaining Data Integrity: How to Specify Unique Constraints for Multiple Columns in MySQL
   In MySQL, a unique constraint enforces data integrity by ensuring that a combination of values in one or more columns is unique within a table
7. Enforcing Data Uniqueness: A Guide to Unique Constraints in PostgreSQL
   In PostgreSQL, you can enforce uniqueness on a column's values within a table using a unique constraint. This constraint ensures that no two rows in the table can have the same value in the specified column