Answer: select * from testtable sample (0);

The question asks which command returns an empty sample. According to Snowflake documentation and the community discussion, the SAMPLE clause accepts a numeric parameter between 0 and 1,000,000, where 0 specifies no rows should be selected, resulting in an empty sample. Option B (SELECT * FROM testtable SAMPLE (0);) correctly implements this by using 0 as the sample size. Option A is invalid syntax as it omits the required numeric parameter. Option C (using NULL) and Option D (using 'none') are not valid parameters for the SAMPLE clause and would result in errors rather than an empty result set. The community discussion shows 100% consensus on B with multiple users confirming it's correct based on documentation and testing.

Author: LeetQuiz Editorial Team