Projection (relational algebra)

In relational algebra, a projection is a unary operation written as ${\displaystyle \Pi _{a_{1},...,a_{n}}(R)}$ where ${\displaystyle a_{1},...,a_{n}}$ is a set of attribute names. The result of such projection is defined as the set obtained when the components of the tuple ${\displaystyle R}$ are restricted to the set ${\displaystyle \{a_{1},...,a_{n}\}}$ – it discards (or excludes) the other attributes.

...
Wikipedia