SQL - グループ化と集約化(フィルタ条件(having節))

初めてのSQL
Alan Beaulieu (著)

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、ISBN4-8733-181-8) の8章(グループ化と集約化),　8.5(練習問題)8-3を解いてみる。

8-3.

SQL文(TextWrangler)

SELECT cust_id, count(*)
FROM account
GROUP BY cust_id
HAVING COUNT(*) >= 2;

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 1
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> SELECT cust_id, count(*)
    -> FROM account
    -> GROUP BY cust_id
    -> WHERE COUNT(*) >= 2;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE COUNT(*) >= 2' at line 4
mysql> SELECT cust_id, count(*)
    -> FROM account
    -> GROUP BY cust_id
    -> HAVING COUNT(*) >= 2;
+---------+----------+
| cust_id | count(*) |
+---------+----------+
|       1 |        3 |
|       2 |        2 |
|       3 |        2 |
|       4 |        3 |
|       6 |        2 |
|       8 |        2 |
|       9 |        3 |
|      10 |        2 |
+---------+----------+
8 rows in set (0.05 sec)

mysql> quit
Bye
$