SQL - グループ化と集約化(複数列でのグループ化)

開発環境

• OS: OS X Lion - Apple
• データベース言語: SQL
• リレーショナルデータベース: MySQL

『初めてのSQL』(Alan Beaulieu 著、株式会社クイープ 翻訳、オライリー・ジャパン、2006年、ISBN4-87311-281-8) の8章(グループ化と集約化),　8.5(練習問題)8-4を解いてみる。

8-4.

入出力結果(Terminal)

$ mysql -u lrngsql -p bank
Enter password: 
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 7761
Server version: 5.5.24 MySQL Community Server (GPL)

Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show tables;
+----------------+
| Tables_in_bank |
+----------------+
| account        |
| branch         |
| business       |
| customer       |
| department     |
| employee       |
| individual     |
| officer        |
| product        |
| product_type   |
| tmp            |
| transaction    |
+----------------+
12 rows in set (0.00 sec)

mysql> desc account;
+--------------------+----------------------------------+------+-----+---------+----------------+
| Field              | Type                             | Null | Key | Default | Extra          |
+--------------------+----------------------------------+------+-----+---------+----------------+
| account_id         | int(10) unsigned                 | NO   | PRI | NULL    | auto_increment |
| product_cd         | varchar(10)                      | NO   | MUL | NULL    |                |
| cust_id            | int(10) unsigned                 | NO   | MUL | NULL    |                |
| open_date          | date                             | NO   |     | NULL    |                |
| close_date         | date                             | YES  |     | NULL    |                |
| last_activity_date | date                             | YES  |     | NULL    |                |
| status             | enum('ACTIVE','CLOSED','FROZEN') | YES  |     | NULL    |                |
| open_branch_id     | smallint(5) unsigned             | YES  | MUL | NULL    |                |
| open_emp_id        | smallint(5) unsigned             | YES  | MUL | NULL    |                |
| avail_balance      | float(10,2)                      | YES  |     | NULL    |                |
| pending_balance    | float(10,2)                      | YES  |     | NULL    |                |
+--------------------+----------------------------------+------+-----+---------+----------------+
11 rows in set (0.05 sec)

mysql> select product_cd,open_branch_id,avg(avail_balance) average
    -> from account
    -> group by product_cd,open_branch_id
    -> order by avg(avail_balance) desc;
+------------+----------------+--------------+
| product_cd | open_branch_id | average      |
+------------+----------------+--------------+
| SBL        |              3 | 50000.000000 |
| CHK        |              4 | 16963.082458 |
| BUS        |              2 |  9345.549805 |
| MM         |              1 |  7416.319824 |
| CD         |              1 |  5750.000000 |
| CD         |              2 |  4000.000000 |
| MM         |              3 |  2212.500000 |
| CHK        |              2 |  1657.885010 |
| CHK        |              3 |  1057.750000 |
| SAV        |              1 |   767.770020 |
| SAV        |              4 |   387.989990 |
| SAV        |              2 |   350.000000 |
| CHK        |              1 |   260.719999 |
| BUS        |              4 |     0.000000 |
+------------+----------------+--------------+
14 rows in set (0.13 sec)

mysql> quit;
Bye
$