ITPEC IP April 2019 Question 27
ITPEC IP April 2019 — Question 27 of 100
Selecting rows whose price is at least 100 yen is the relational operation called selection. Selection filters tuples, or rows, according to a condition while retaining the table's columns; here the condition is Price >= 100.
Answer (c)
Why not others:
- join combines related rows from two tables
- projection chooses particular columns rather than filtering rows
- union combines the rows of two union-compatible relations
Key rule: In relational algebra, selection filters rows and projection filters columns.
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