SQL Sorting and Limiting Results 3

Question 1

How are NULL values typically sorted in PostgreSQL ascending order by default?

Accepted Answer

NULLs appear last

Answer

In PostgreSQL ascending order, NULLs are treated as larger and sort last by default.

Question 2

Which clause forces NULL values to appear first in PostgreSQL?

Accepted Answer

ORDER BY col NULLS FIRST

Answer

NULLS FIRST explicitly places NULL values before non-NULL values.

Question 3

Can you ORDER BY a column that is not in the SELECT list?

Accepted Answer

Yes, in most databases

Answer

Most databases allow sorting by columns not included in the SELECT list.

Question 4

Which standard SQL clause limits rows using FETCH?

Accepted Answer

FETCH FIRST n ROWS ONLY

Answer

FETCH FIRST n ROWS ONLY is the ANSI SQL standard for limiting rows.

Question 5

What does ORDER BY salary DESC, hire_date ASC do?

Accepted Answer

Highest salary first, ties broken by earliest hire date

Answer

Primary sort is salary descending; ties are resolved by hire_date ascending.

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