셀렉션

1 개요

selection, restriction

셀렉션, 선택

• 표 안의 행을 추출하는 연산

[math]\displaystyle{ Person }[/math]	[math]\displaystyle{ \sigma_{Age \ge 34}( Person ) }[/math]	[math]\displaystyle{ \sigma_{Age = Weight}( Person ) }[/math]
Name Age Weight Harry 34 80 Sally 28 64 George 29 70 Helena 54 54 Peter 34 80	Name Age Weight Harry 34 80 Helena 54 54 Peter 34 80	Name Age Weight Helena 54 54

2 같이 보기

• SQL SELECT
• Generalized selection
• JOIN
• 프로젝션 (관계대수)

3 참고

• https://en.wikipedia.org/wiki/Selection_(relational_algebra)