https://documents.lucid.app/documents/f758098f-4a70-48df-a7f7-d71e3cd9bf41/pages/22QjwE7Q61XT?a=662&x=-233&y=646&w=847&h=388&store=1&accept=image%2F*&auth=LCA 20eec7b6351c7c02728835aef0f8d413f65828565bda2273376bd69a923d54c4-ts%3D1710498983

Renaming attribute

$$ \rho_{Y \leftarrow X}R $$

Example 1:

Collect all the IDs in university

$\rho_{student \leftarrow SIds} \cup \rho_{Professor \leftarrow ProfIds}$

Example 2:

Projection, Selection

Selection

Filter some tuples on the base of Property $F$

$\sigma_F(R)$ \\sigma_F(R)where

• $F$ is cardinality depends on the property

• $R$ is schema

Projection

Produce results over a subset of the attributes of the operand, with values from all its tuples

$\pi_Y(R)$ \\pi_Y(R) where

• Given a relation $R(X)$, $Y$ is a subset of X

• $R$ is schema

Example:

$\sigma_{\texttt{Country="IT"}}(Student)$