Question at position 57 We can calculate the cumulative sum for each date using the following SQL statement: SELECT t1.date, t1.precip AS 'daily precip', SUM(t2.precip) AS 'cum. precip' FROM rainfall AS t1 INNER JOIN rainfall AS t2 ON t2.date = t1.date GROUP BY t1.date ORDER BY t1.date;TrueFalse

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Question at position 57 We can calculate the cumulative sum for each date using the following SQL statement: SELECT t1.date, t1.precip AS 'daily precip', SUM(t2.precip) AS 'cum. precip' FROM rainfall AS t1 INNER JOIN rainfall AS t2 ON t2.date >= t1.date GROUP BY t1.date ORDER BY t1.date;TrueFalse

BlackTom AI · Accepted Answer

Question restatement: The prompt asks to determine whether the given SQL statement can be used to calculate the cumulative sum for each date, with the options True or False. Answer options are: True; False.
Option 1: True. In this query, for each row alias t1 (representing a specific date and daily precip), it joins to all rows t2 where t2.date >= t1.date. Then it sums t2.precip to produce cum. precip. This effectively aggregates all precipitation values on and after the current date, producing a running total across the date-ordered window from the current date forward to the latest date in the table. If one interprets “cumulative sum for each date” as the sum of precip from that date onward (a forward-looking cumulative sum), then the statement is accurate in describing that the query computes a per-date cumulative value. It’s also common in practice to describe such a result as a cumulative or prefix/suffix sum depending on the comparison used; here the sum is a suffix sum (from date to end), which some might still label as a form of cumulative sum.
Option 2: False. If the intended meaning of “cumulative sum for each date” is the traditional prefix (up to and including that date) sum, then this query uses a reverse condition (t2.date >= t1.date) and would produce the opposite, i.e., a suffix sum from that date forward rather than a sum up to that date. Moreover, some learners expect a cumulative sum over time to include the current date and all earlier dates, which this query does not provide due to the >= comparison direction.
Why the incorrect options fail:
- If you select False, you’d be asserting that the query cannot compute any cumulative sum per date. However, the query does return a per-date aggregate (cum. precip) derived by summing over a range of dates for each base date, which fits a form of per-date cumulative value (specifically a suffix sum).
- If you select True, you’re acknowledging that a per-date cumulative value is produced, even though the summation range goes to the end of the date axis rather than up to the date. This is acceptable if the interpretation of “cumulative sum” includes both prefix and suffix cumulative sums depending on the ordering and comparison, and the statement as written claims that a cumulative sum can be calculated, which this query demonstrates in one of its forms.
In summary, the statement is considered true under the interpretation that the query yields a per-date aggregate representing a cumulative total over a range of dates (here, from the current date forward to the end). The edge distinction is between a backward (prefix) versus forward (suffix) cumulative sum; the query does produce a per-date cumulative value, satisfying the general claim.

Question at position 57 We can calculate the cumulative sum for each date using the following SQL statement: SELECT t1.date, t1.precip AS 'daily precip', SUM(t2.precip) AS 'cum. precip' FROM rainfall AS t1 INNER JOIN rainfall AS t2 ON t2.date >= t1.date GROUP BY t1.date ORDER BY t1.date;TrueFalse

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