Crowdly

SELECT and FROM

SELECT and WHERE

WHERE and GROUP BY

Use the following relations R and S to answer the question:

Compute R ⋈ S. Which of the following records will be in the result?

6, 4, 4, 1

2, 3, 3, 5

100%

3, 3, 1, 6

3, 5, 3, 1

Use the following relations R and S to answer the question:

Compute π_{B, C}(R ⋈ S). Which of the following records will be in the result?

6, 4

5, 3

4, 3

5, 6

What is the effect of SELECT DISTINCT propertyNo FROM Viewing?

It eliminates null property numbers from the result.

It sorts the property numbers in ascending order.

It eliminates duplicate property numbers from the result.

It counts the number of distinct properties.

(Note: R.A means the attribute A of the relation R.)

Use the following relations R and S to answer the question:

Compute R ⋈_R.A<S.C S. [this is theta join]. Which of the following records will be in the result?

6, 4, 3, 1

6, 4, 4, 1

2, 3, 3, 5

3, 5, 1, 6

Use the following relations R and S to answer the question:

Compute R ⋈_R.A<S.C S. [this is theta join]. Which of the following records will be in the result?

(Note: R.A means the attribute A of the relation R.)

6, 4, 3, 1

6, 4, 4, 1

2, 3, 3, 5

3, 5, 1, 6

In ORDER BY type_, rent DESC, what role does rent play?

It filters out rows whose rent is null.

It is a minor (secondary) sort key applied within each property type.

It is the primary sort key.

It groups rows by rent before sorting.

How do you correctly test whether no comment was supplied (i.e. comment_ is missing)?

WHERE comment_ IS NULL

WHERE NULL(comment_)

WHERE comment_ == NULL

WHERE comment_ = NULL