Databases, tables, and relationships
A database management system stores and queries structured data while applying rules to keep it useful.
Learning objectives
- Define DBMS, table, row, column, and schema.
- Explain why separate related tables beat repeated unstructured files.
Structure supports questions
A relational database represents a table as rows of records and columns of attributes. A schema specifies the structure and constraints. For example, a students table may have an identifier, name, and department; an enrollments table can relate students to courses.
Why relationships matter
Storing a department’s full name in every student row repeats data and risks inconsistency. A relationship lets tables refer to shared facts through keys. This is not a reason to split every value into its own table; modeling is a balance between integrity and the queries a system needs.