题解 | #统计作答次数#
统计作答次数
https://www.nowcoder.com/practice/45a87639110841b6950ef6a12d20175f
# 统计出总作答次数total_pv、
# 试卷已完成作答数complete_pv、
# 已完成的试卷数complete_exam_cnt。
SELECT
COUNT(id) AS total_pv,
COUNT(score) AS complete_pv,
(SELECT
COUNT(DISTINCT exam_id)
FROM exam_record
WHERE score IS NOT NULL
)AS complete_exam_cnt
FROM exam_record
