SQL - 条件ロジック(検索 case 式)

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11章(条件ロジック)、11.4(練習問題)11-1を解いてみる。

11-1.

SQL文(BBEdit)

SELECT emp_id,
  CASE 
    WHEN 
      title LIKE "%President" OR
      title = 'Treasurer' OR
      title = "Loan Manager" THEN 'Management'
    WHEN 
      title LIKE "Operations%" OR
      title LIKE "%Teller"  THEN 'Operations'
    ELSE "UNKNOWN"
  END title
FROM employee;

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 4
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 emp_id,
    ->   CASE 
    ->     WHEN 
    ->       title LIKE "%President" OR
    ->       title = 'Treasurer' OR
    ->       title = "Loan Manager" THEN 'Management'
    ->     WHEN 
    ->       title LIKE "Operations%" 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 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> quit
Bye
$