Relational Algebra

Relational Algebra in DBMS:

• Selection (σ): Selects a subset of rows (tuples) from a relation that satisfy a given condition. Corresponds to the `WHERE` clause in SQL.
• Projection (π): Selects certain columns (attributes) from a relation and discards the other columns. Corresponds to the `SELECT` list in SQL.
• Union (∪): Combines two relations and returns all unique rows from both. The relations must be compatible (same number of columns and compatible data types).
• Set Difference (−): Returns all rows that are in the first relation but not in the second.
• Cartesian Product (×): Combines each row of one table with each row of another table.
• Join (⨝): Combines rows from two or more tables based on a related column between them. Natural Join is a common type that joins tables based on their common attributes.