### [Relational Algebra - Recap](obsidian://open?vault=Computer%20Science%20Year%201&file=Semester%201%2FDatabase%20Systems%2FWeek%2010%2FWeek%2010)

- High level & procedural
- Defines how to build relations

#### Data Manipulation Language

- Provides set of operations
- Data retrieval - query language
- ex. SQL

#### Closure

- Operations work on one or more relations to define another relation without changing the original
- Both operands and results are relations, output from one operation can become the input for another operation.
- This allows nested expressions.