MYSQL子查询例题以及答案

More Subqueries Quizzes

Above is the ERD for the database again - it might come in handy as you tackle the quizzes below. You should write your solution as a subquery or subqueries, not by finding one solution and copying the output. The importance of this is that it allows your query to be dynamic in answering the question - even if the data changes, you still arrive at the right answer.

1. 1. Provide the name of the sales_rep in each region with the largest amount of total_amt_usd sales.

      SELECT * FROM
      (SELECT rname rname,MAX(totalsum) totalsum
      FROM
      (SELECT r.name rname,s.name sname,SUM(total_amt_usd) totalsum
      FROM accounts a
      JOIN orders o
      ON o.account_id = a.id
      JOIN sales_reps s
      ON a.sales_rep_id = s.id
      JOIN region r
      ON r.id = s.region_id
      GROUP BY r.name,s.name
      ORDER BY 1,3 desc ) sub
      GROUP BY rname ) t1
      JOIN
      (SELECT r.name rname,s.name sname,SUM(total_amt_usd) totalsum
      FROM accounts a
      JOIN orders o
      ON o.account_id = a.id
      JOIN sales_reps s
      ON a.sales_rep_id = s.id
      JOIN region r
      ON r.id = s.region_id
      GROUP BY r.name,s.name
      ORDER BY 1,3 desc ) t2
      ON t1.rname = t2.rname
      WHERE t1.totalsum = t2.totalsum
      
      METHOD2

      WITH t1 AS (SELECT rname rname,MAX(totalsum) totalsum
      FROM
      (SELECT r.name rname,s.name sname,SUM(total_amt_usd) totalsum
      FROM accounts a
      JOIN orders o
      ON o.account_id = a.id
      JOIN sales_reps s
      ON a.sales_rep_id = s.id
      JOIN region r
      ON r.id = s.region_id
      GROUP BY r.name,s.name
      ORDER BY 1,3 desc ) sub
      GROUP BY rname ),

      t2 AS (SELECT r.name rname,s.name sname,SUM(total_amt_usd) totalsum
      FROM accounts a
      JOIN orders o
      ON o.account_id = a.id
      JOIN sales_reps s
      ON a.sales_rep_id = s.id
      JOIN region r
      ON r.id = s.region_id
      GROUP BY r.name,s.name
      ORDER BY 1,3 desc )

      SELECT *
      FROM t1
      JOIN t2
      ON t1.rname = t2.rname
      WHERE t1.totalsum = t2.totalsum

2. For the region with the largest (sum) of sales total_amt_usd, how many total (count) orders were placed?

3. For the name of the account that purchased the most (in total over their lifetime as a customer) standard_qty paper, how many accounts still had more in total purchases?

4. For the customer that spent the most (in total over their lifetime as a customer) total_amt_usd, how many web_events did they have for each channel?

5. What is the lifetime average amount spent in terms of total_amt_usd for the top 10 total spending accounts?

6. What is the lifetime average amount spent in terms of total_amt_usd for only the companies that spent more than the average of all orders.