1Z0-071 Set Operators

Question 1

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

Accepted Answer

UNION ALL

Answer

UNION

Answer

INTERSECT

Answer

MINUS

Question 2

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

Accepted Answer

INTERSECT

Answer

UNION

Answer

UNION ALL

Answer

MINUS

Question 3

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

Accepted Answer

MINUS

Answer

UNION

Answer

UNION ALL

Answer

INTERSECT

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

Both queries must reference the same tables

Answer

The ORDER BY clause must be present in each SELECT

Answer

Both queries must have identical WHERE clause conditions

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

The last SELECT statement

Answer

Alphabetical order of all column names

Answer

The SELECT statement that returns the most rows

Question 6

Where must the ORDER BY clause be placed when used with set operators in Oracle SQL?

Accepted Answer

Only at the very end of the entire compound query

Answer

Before the first SELECT statement

Answer

After each individual SELECT statement

Answer

ORDER BY cannot be used with set operators

Question 7

What happens when corresponding columns in a UNION query have completely incompatible data types (for example, DATE and NUMBER)?

Accepted Answer

An ORA-01790 error is returned

Answer

Oracle uses the data type from the first SELECT

Answer

Oracle converts all values to VARCHAR2 automatically

Answer

NULL values replace rows with incompatible types