SQL - 条件ロジック(単純case式と検索case式)

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11章(条件ロジック),　11.4(練習問題)11-1を解いてみる。

11-1.

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 3
Server version: 5.5.18 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> desc employee;
+--------------------+----------------------+------+-----+---------+----------------+
| Field              | Type                 | Null | Key | Default | Extra          |
+--------------------+----------------------+------+-----+---------+----------------+
| emp_id             | smallint(5) unsigned | NO   | PRI | NULL    | auto_increment |
| fname              | varchar(20)          | NO   |     | NULL    |                |
| lname              | varchar(20)          | NO   |     | NULL    |                |
| start_date         | date                 | NO   |     | NULL    |                |
| end_date           | date                 | YES  |     | NULL    |                |
| superior_emp_id    | smallint(5) unsigned | YES  | MUL | NULL    |                |
| dept_id            | smallint(5) unsigned | YES  | MUL | NULL    |                |
| title              | varchar(20)          | YES  |     | NULL    |                |
| assigned_branch_id | smallint(5) unsigned | YES  | MUL | NULL    |                |
+--------------------+----------------------+------+-----+---------+----------------+
9 rows in set (0.00 sec)

mysql> select title from employee
    -> ;
+--------------------+
| title              |
+--------------------+
| President          |
| Vice President     |
| Treasurer          |
| Operations Manager |
| Loan Manager       |
| Head Teller        |
| Teller             |
| Teller             |
| Teller             |
| Head Teller        |
| Teller             |
| Teller             |
| Head Teller        |
| Teller             |
| Teller             |
| Head Teller        |
| Teller             |
| Teller             |
+--------------------+
18 rows in set (0.00 sec)

mysql> select emp_id,
    -> case
    ->   when title like '%President' or
    ->        title = 'Treasurer' or
    ->        title = 'Loan Manager' then 'Management'
    ->   when title = 'Operations Manager' or
    ->        title like '%Teller' then 'Operations'
    ->   else 'Unknown'
    -> end title
    -> from employee;
+--------+------------+
| emp_id | title      |
+--------+------------+
|      1 | Management |
|      2 | Management |
|      3 | Management |
|      4 | Operations |
|      5 | Management |
|      6 | Operations |
|      7 | Operations |
|      8 | Operations |
|      9 | Operations |
|     10 | Operations |
|     11 | Operations |
|     12 | Operations |
|     13 | Operations |
|     14 | Operations |
|     15 | Operations |
|     16 | Operations |
|     17 | Operations |
|     18 | Operations |
+--------+------------+
18 rows in set (0.00 sec)

mysql> select emp_id,
    -> case title
    -> when 'President' then 'Management'
    -> when 'Vice President' then 'Management'
    -> when 'Treasurer' then 'Management'
    -> when 'Loan Manager' then 'Management'
    -> when 'Operations Manager' then 'Operations'
    -> when 'Head Teller' then 'Operations'
    -> when 'Teller' then 'Operations'
    -> else 'Unknown'
    -> end title from employee;
+--------+------------+
| emp_id | title      |
+--------+------------+
|      1 | Management |
|      2 | Management |
|      3 | Management |
|      4 | Operations |
|      5 | Management |
|      6 | Operations |
|      7 | Operations |
|      8 | Operations |
|      9 | Operations |
|     10 | Operations |
|     11 | Operations |
|     12 | Operations |
|     13 | Operations |
|     14 | Operations |
|     15 | Operations |
|     16 | Operations |
|     17 | Operations |
|     18 | Operations |
+--------+------------+
18 rows in set (0.00 sec)

mysql> quit;
Bye
$