SQL / RA

Question 1

Selection

Answer 1

WHERE

σ (sigma)

Question 2

Projection

Answer 2

SELECT attribute list

π (pi)

Question 3

Difference

Answer 3

none

RA “−”

Question 4

JOIN

Answer 4

at least one

⋈

Question 5

DIVISION

Answer 5

all

÷

Question 6

WHERE vs HAVING

Answer 6

Before vs After the crowd
WHERE filters rows.
HAVING filters groups.