1Z0-071 Aggregating Data with Group Functions

Question 1

Which GROUP BY function returns the total sum of a numeric column?

Accepted Answer

SUM()

Answer

SUM() adds up all non-NULL numeric values in the specified column.

Question 2

What happens to NULL values when using the AVG() function in Oracle SQL?

Accepted Answer

They are ignored entirely

Answer

Oracle's AVG() function ignores NULL values and calculates the average of only non-NULL rows.

Question 3

Which clause is used to filter the results of a GROUP BY query?

Accepted Answer

HAVING

Answer

The HAVING clause filters groups after aggregation, unlike WHERE which filters rows before grouping.

Question 4

What does the COUNT(*) function return?

Accepted Answer

Total number of rows including NULLs

Answer

COUNT(*) counts every row in the result set regardless of NULL values in any column.

Question 5

Which statement about the GROUP BY clause is TRUE?

Accepted Answer

Columns in SELECT not in an aggregate must appear in GROUP BY

Answer

Any non-aggregated column in the SELECT list must also appear in the GROUP BY clause.

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