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Question 177

Which two are true about scalar subquery expressions?

They can return at most one row.

You must enclose them in parentheses.

You cannot correlate them with a table in the parent statement.

They can return two columns.

You can use them as a default value for a column.

Correct Answer: A, B

Scalar subquery expressions can return at most one row and must be enclosed in parentheses. These expressions are used as single values within another SQL expression. They cannot return more than one row, making them scalar. Using parentheses is mandatory to distinguish the subquery from other parts of the SQL statement. Correlation with a table in the parent statement is allowed, meaning they can refer to columns in the outer query.

Discussion

CyberPOptions: AB

https://www.examtopics.com/discussions/oracle/view/20447-exam-1z0-071-topic-2-question-55-discussion/

lucemqyOptions: AB

AB is the correct answer

alic_alexOptions: AB

correct A,B,C - https://docs.oracle.com/database/121/SQLRF/expressions014.htm#SQLRF52093

karols32

You can't corralate scalar subquery expression with outer query. This is the point. Main difference between scalar subquery expression and corraleted subquery expression is that the first one can't be join. If you join scalar subquery expression automaticly it changes in corraleted subquery expression. Correct: A,B.

mrcsp

Surely you can correlate, the alternative says you CANT, correlate is not only JOIN select * from employees e where maximum_permitted_absence < (select sum(days_absent) from absences a where a.emp_id = e.emp_id)