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统计复旦用户8月练题情况关于复旦为什么不放ON里

# 外连接 select up.device_id, up.university, COALESCE(COUNT(qpd.question_id), 0) AS question_cnt, COALESCE(SUM(CASE WHEN qpd.result = 'right' THEN 1 ELS...

2024-01-21

1 159

题解 | #浙大不同难度题目的正确率#

select qd.difficult_level, ROUND(COUNT(if (qpd.result = 'right',1,NULL))/COUNT(qpd.result),4) #对的行数 / 总行数 AS correct_rate FROM user_profile AS up JOIN...

2024-01-21

0 161

题解 | #统计复旦用户8月练题情况#

# 外连接 select up.device_id, up.university, COALESCE(COUNT(qpd.question_id), 0) AS question_cnt, COALESCE(SUM(CASE WHEN qpd.result = 'right' THEN 1 ELS...

2024-01-21

0 147

题解 | #返回每个顾客不同订单的总金额#

select od.cust_id, sum(ot.item_price * ot.quantity) AS total_order from Orders AS od JOIN OrderItems AS ot ON od.order_num = ot.order_num GROUP BY od...

2024-01-21

0 314