1Z0-071 Set Operators

Question 1

Which set operator returns all rows from both queries, including duplicate rows?

Accepted Answer

UNION ALL

Answer

UNION ALL combines result sets from both queries and retains all duplicate rows without performing any deduplication.

Question 2

Which set operator returns only the rows that appear in both result sets?

Accepted Answer

INTERSECT

Answer

INTERSECT returns only the rows that are common to both SELECT statements, eliminating rows unique to either query.

Question 3

Which set operator returns rows from the first query that do NOT appear in the second query?

Accepted Answer

MINUS

Answer

MINUS (Oracle-specific) returns all distinct rows selected by the first query that are not present in the second query result.

Question 4

When combining two SELECT statements with a set operator, which of the following is a mandatory requirement?

Accepted Answer

Both SELECT statements must return the same number of columns

Answer

All set operators require that both SELECT statements return the same number of columns for the operation to execute successfully.

Question 5

In a compound query using set operators, the column headers in the final result are determined by which SELECT statement?

Accepted Answer

The first SELECT statement

Answer

Oracle uses the column names or aliases from the first SELECT statement to label the columns in the combined result set.

1Z0-071 - Oracle Database SQL Certified Associate Practice Test